Andrew,

strange, web git interface thinks that 

cinelerra-5.1/thirdparty/src/libsvtav1-v2.2.1.tar.xz [moved from cinelerra-5.1/thirdparty/src/ffmpeg-6.1.tar.xz with 55% similarity] diff | blob | history

I think it should be just new file?

Yes, I did not like this either but was not comfortable trying to fix it.  I finally deleted the ffmpeg 5.1 and 6.1 large tar files at the same time as adding the updated library and apparently GIT made this erroneous decision. I try to do a new build after a GIT checkin just to verify that I did not make a mistake, and it all seemed OK so I did not worry about it.  But I still do not like it.