Created attachment 158830 [details]
Screen shot.  Clip monitor, upper left.  Project monitor showing applied transformation, upper right.  Render without rescale, lower left.  Render with rescale, lower right.

SUMMARY

While rendering, if the rescale option is enabled, transform effects produce the upper left part of the frame rather than a rescaled version of the effect's output.

This bug was introduced recently.  Renders from April 11 were fine, renders from April 27 of the same project, unchanged, are exhibiting the problem.


STEPS TO REPRODUCE
1. New project, past image into time line.
2. Add a transform effect and adjust the scale and position
3. Render with Video Rescale option enabled.

OBSERVED RESULT
When rendering with rescale on, transform effects are applied incorrectly.  It looks like they don't get rescaled with the rest of the video, and instead the upper-left portion of the transform's output is rendered.

EXPECTED RESULT
Rendered video always resembles that in the project monitor window.

SOFTWARE/OS VERSIONS
Linux Mint 21.1 with FlatPak install of KdenLive.  I'm good about staying up-to-date with releases.