As we know Bandicam is a really laggy recording software, so I feel like it might affect the timing of the run, using a frame timer.

It wouldn’t really affect the frame timer that much unless the category’s competition is really tight. In that case, you can make rules to have a certain framerate.

I don't see a reason unless it's within a second or two of first place. Unless you're asking this because it could make splicing easier to hide? Though even then I don't think it applies.

Really depends on how choppy the recording is. 20fps? 10fps? 30fps with random stutters?

rejecting a run because its recorded with bandicam is dumb. only reject it for the video if its unwatchably laggy or so bad quality you cant make sense whats happening