Apologies for not quite figuring out how to post this information or that information but when I tried to run 1.16.4 with the latest version of Forge while using the most recent update of Stack Refill version 1.16.5-1.2 a crash error screen popped up saying that this version "needs language provider javafml:36 or above to load". I'm not quite tech savvy but I'll figure out how to post everything eventually. Sorry about this inconvenience.

Apologies for making this issue... I see what I have done wrong.

... Or maybe not... The same crash error occured... X / I thought it might be because I am using the recommended version of Forge and not the Latest version of Forge but that didn't seem to work either.

You'll need Forge 1.16.5 to run the updated mod. But 1.16.5 should be compatible with most mods of 1.16.4. Sorry for the inconvenience.