Vertically scrolling luma flicker distortion in EP?
 

I've seen this before in other situations, but noticed it again on an HR-S9800U when playing a random old EP tape and would like to know what it is called or what causes it as I think it is common enough that many of you probably have seen/dealt with it before.

Video attached is a phone video of a screen, but it's easy enough to see it there.

Chain is just an HR-S9800U directly to WFM90 via composite.

That same VCR plays SP tapes without any issues to the same monitor.

I'd have to guess that this is some sort of AC line interference given the repeating pattern, but I'm a little perplexed as to why it would do it in EP, but not SP? I understand that it could be the tape itself has it baked in, but if it did, how would you go about improving it?

Is there an established name for this type of horizontal "flicker" / "vertically scrolling luma variance"?

can't see nothing, upload a normal capture

It's called moire if that's what you are talking about, This happens when native resolution and display resolution are slightly different, Post a clip of the capture, This is probably because you are using a low resolution display.