I'm using the latest version for 1.18.2

I tested it on two different servers and on both enabling the setting "optimizedRecipeManager" would break furnaces: They just don't smelt anything. As soon as I disable the setting they work again.

Same here. I had a bunch of other mods and it made it very hard to troubleshoot.
I thought it would have been the optimize furnace setting, but it wasnt.

This has been fixed internally and should be committed today. I may be releasing a version with the fix today.