Video out of sync

Hello

after several tries all my videos are not in sync I tried via mp4 and png output however I can’t get the audio and video synchronized together

the video source is a cartoon at 24fps

Same on Mac. It makes it quite unusable as the finished product must be getting stretched somehow

I’ve got some old 320x240 15 fps video from about two decades ago that I’m trying to enhance to 640x480, and while I have a workaround for the video (turning it to MP4 first) so the visual part looks good, the audio keeps slipping and losing sync!

Is this a problem other people have? And can it be fixed?