After reading the mail list, I thought that some test cases are needed to test plugins after migrating from ffmpeg 6.1 to 7.0.  And then compare the new videos with the old ones in semi-automatic mode.

I found that ffmpeg a able to produce diff-like videos with the blend filter for video: https://stackoverflow.com/questions/25774996/how-to-compare-show-the-difference-between-2-videos-in-ffmpeg