I was able to reproduce this on both 1.12 and 1.16. Breaking the proxy while having a redstone writer powering redstone through it will cause the redstone to remain powered until an update happens to it. You have to break the proxy first.

Oh yea, I shouold do an update when the block break

Working with redstone in game is a huge pain, I wouldn't even want to imagine how painful it is in the code base.

Ugh, the problem is solved, but my network is being a little funny about github, I can't push the changes...