Quite common for this to happen. The usual advice is when the racquet head hits the shuttle, it is totally face on the shuttle in the direction you want to hit it. You can experiment that when hitting the shuttle, the left edge of the racquet head turns slightly forward just as you hit the shuttle. Another experiment is to hit the shuttle very slightly left of the centreline of the shuttle. When you try these, it will force you to use for your fingers a bit differently to make it work. On other note, just a reminder that the shadow overhead stroke next the wall is done to force your elbow to reach up higher to the shuttle. Tilt your shoulders to make the extra height upwards. Definitely do not use your old technique of having the elbow out to the side to play the overhead.
Reasons for a cut is a big subject that I addressed a bit in what you quoted.. it's obviously not as simple as saying "grip" or "bad technique", because you cut some and not others there. And at some point asking why you cut it could be like a philosophical question like yesterday you drank something using a straw and today you drank something with a straw but today you put the straw in a slightly different part of your mouth, why did you do that. Or you were drinking from it, you took the second sip from the straw and the straw went into a marginally different part of the mouth, why did that happen. And one can get into questions about free will and to what extent we know why we do what we do.. And you'd know your own mind better than somebody else. Why you might have moved something or some things by half a centimetre. Humans aren't robots designed for badminton. And even top players can cut it unintentionally sometimes If you are aware you did it then you can "choose" or "make a decision", to not do it, or have an intention to not do it given an understanding of what you did. You ask if the reason is the head being flat or something else. Cutting is when the racket face doesn't point in the same direction as your swing. So e.g. swinging straight where you want, but racket face pointing off. It's extremely clear in the image that your racket face is pointing off. It's not even a question. Tiny movements with your arm could change that racket face angle and eliminate the cut. As I said in what you quoted, I don't think you should focus on that question at all. I think you should focus on what has been suggested already regarding your elbow position on contact. Unintentional cutting is to be expected it happens to everybody. Just something it helps to be aware of and you are lucky enough to have an image of yourself doing it, from a video you have, then thats help you notice in future if you do so.. So if somebody says "you cut it" then you don't have to sit there scratching your head wondering what they are talking about, you can check it for yourself at the timeframe in a video where they said it. And you can see exactly what they are talking about. All the great players prior to smartphones didn't have that luxury. And top players now even with the luxury of smartphones sometimes still cut it unintentionally sometimes(they'd hear it and see the shuttle trajectory didn't match their intention). And besides bad technique but also really good technique can in some ways increase risk of cutting, as there's a lot going on, and anything being off by an inch or 10 degrees or some small number, maybe even millimetres, could cause a cut. You can look at your racket face and move it the little fractions required to not cut it. Within 100 years, maybe even within 50 years, there will be brain interfacing technology to ensure that unintentional cuts don't happen, as well as robots designed to play badminton and that don't unintentionally cut it. But science isn't there yet.
Some reinforcement on early preparation of the overhead and elbow position by Viktor Axelsen https://www.instagram.com/reel/C3Ru1PAyG6N/?igsh=cXkxeWpzbnN3aXpl
I was once told the prep for a round the head is a bit different..but one can do the prep the same. He is doing the prep the same. The contact point is a bit different with a round the head and there might be a slight difference when it comes to side bending.. Would be a bit preferable if the demo was for the same shot OP is doing, so forehand side. Viktor's one at that instagram link is (as he says in the video), a RTH shot.
I wasn't writing a suggestion or advice there , so when you say yes to me, I don't think you are saying yes to what I wrote. My post was a reply to you not a suggestion or advice to pavilto or anybody. Secondly, If wanting to put things in such terms as elbow height re what i was saying, which I wouldn't normally do when making the point I was making, then Actually I think maybe many would have the elbow higher on the RTH side than on the FH side , for a shorter swing on the RTH side. And as mentioned, I've sometimes been coached a slightly different prep on the RTH side but anyhow. (So I wouldn't even describe a specific RTH prep as elbow higher than on FH side, though technically it would be, but there are other more significant differences if doing a different prep for RTH). Focussing on a different RTH prep is not necessary. Pavilto's shot isn't a RTH. And if racket prep is done the same both sides then by definition the elbow is at the same place both sides. One of my other points was that there would be side bending on a RTH. And your video of Viktor is him doing a RTH. Whether there is side bending on the FH side is another matter. I think for FH side, maybe it can vary depending on the shot. Pavilto's shot was a FH on the FH side. And I mention side bending cos you talked sometimes about "shoulder tilt". But what you mean is side bending. Bending with the lower back or at the hip. Eg you don't mean shoulder elevation one side and shoulder depression the other side!
For a forehand on the forehand side, "tilt the shoulders"(/side bending), looks to me to be more of an icing on the cake, that can be done for a bit more height if a scenario where you can be positioned for it.. But If something is significantly wrong in the swing like an elbow pointing forwards(as in the earlier pic of pavilto's dry swing) , that's more of a significant issue than not doing a "shoudler tilt" for a forehand on the forehand side. e.g. here are two examples of perfectly good swings without a "shoulder tilt"/side bending. There are many with side bending/"shoulder tilt" too e.g. here are two. The second one has it only a bit. If the swing is good(nothing funny going on like an elbow pointing forwards) then a shoulder tilt for a FH on the FH side, in a scenario when they can be positioned for it, can add a bit of iceing on the cake.
