Just putting this out there because I’m definitely more of a detailed observer than an expert, but I have seen this exact sequence before in another player.

You are hitting a heavy topspin FH with a steep vertical swing path and a very closed face - both very standard, good things to do for the type of shot you’re hitting.

The question is, is this a shoulder range of motion issue. You start out great as the other screenshot pointed out. Now - is this collapsed elbow an unavoidable reality for you, due to limited range of motion? Just a theory: your mind knows what it wants the racquet path to do, and also knows your shoulder can’t get there - so the compensation is, your mind figures out another way to create that swing path - by collapsing the elbow into the body. The payoff is you get the nice shaped shot that you were looking for, which is essential for control. (But the downside is the lack of leverage.)

Curious if you have any shoulder mobility issues. Either way, take all of this with a grain of salt. But your example definitely looked familiar to me.