When cutting a clip, using the razor tool or shift-R, and then speeding up the new (right most) clip, the first frame of the new clip is "wrong" in the sense that it seems to be a duplicated frame from the left clip.

In my tests, I could see that the more I speed up the clip, the further back into the left clip the first frame is. (this is kinda hard to explain...)
This behavior results a very noticeable one frame "back in time" followed by the rest of the clip sped up.

For example:
- given a 3s clip at 4k 30fps (pretty sure it happened with other clips too, but that's what I have with me here)
- cut at the 00:00:02.00 mark
- speed up the last 1s part 400%
- The first frame of the last part is now the same frame as the one at 00:00:01.27 in the first clip
- ctrl-z
- speed up the last part 800%
- first frame is now the same as the one at 00:00:01.23

Strangely, with my test clip, if I speed up 700%, it seems to work fine, or at least skip forward instead of backwards.


SOFTWARE/OS VERSIONS
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2
kdenenlive: built from git 2021-12-02