I have this server on Aternos with origins and some other mods and I picked feline, and the night vision is spazzing out like hell.
I didn't know a side-effect to picking feline was having seizures every time night comes :/
Anyways I suspect it might be that the timer on the night vision is kept under 10 secs and the warning flicker at the end of night vision is stacking.

This can also happen in the sky

yep, that's what I mean when I said when it's nighttime, corrected the comment.
I wonder when the devs are going to see this?

This happens when it's raining at sunset

This happens when it's raining at sunset

no, it always happens when it's outside and when either in a cave or outside
and also it only seems to happen on 1.17 ver

This can also happen in the sky

This is now fixed.