The Best way to explain this is look at this issue on ae2 github AppliedEnergistics/Applied-Energistics-2#4991

Not sure if its the same issue but I'm running forge 36.0.40 with Quark 2.4-305 and I'm getting in-game chat spam saying my config is not correct and to try /reload or restart the game both of which do not fix it.
config folder has a bunch of .bak config files that got created as well,

right now im roiling back to 304 to see if it resolves it but curious if there is a specific forge version this was tested on or if it is the same issue.

@b52src Forge's Owner explains here whats going on ShetiPhian/Localizations-and-Issues#293

@Vazkii The new version of quark is still doing the .bak file on new versions of forge for 1.16.5
https://i.imgur.com/w3Q5wgd.png