Update on the issue (and the solution)
It seems like a possible solution (at least to me) is to probably avoid having a generator tab open with so many comment frames at once, as they're constantly filling up the whole TCP connection with requests for listening for new comments every time, which is what's causing the "stalled" problem every time I load and save generators.
See this comment for a reference.
Update 1: Now I've just sort of reproduced this by opening the Comments Plugin tab while one of my generators is saving, and then after the tab is being open and then closed, the saving process just stalled out of nowhere.
Recently I was hit by the problem where the saving process just stuck in the background, and when I checked the DevTools Network, there's a lot of stalled connections when fetching a few resources required for the generator page to fully load. The stall eventually ends for a short time (1-30 min), but sometimes even longer (30-60 minutes), and even after that, it's either still hangs on "saving" whatsoever, or it rolls back to the perviously "unsaved" state.
I also got the problem with loading generators too, where it hangs very frequently now, for the same reason, except that I sometimes get an ERR_QUIC_PROTOCOL_ERROR
from the console whenever the generator fails to load after the stalled connections.
Is this maybe just because of the internet connection, my browser, or probably the "cache-busting" issue in the end? I tried logging into my other browser (Firefox) and saving the same generator and found no issues. It also loads generators perfectly fine.