Took me a few hours to sort through my mods and narrow this issue down. When Alex's Mobs 1.18.1 is loaded, I experience the following issues:

When crafting items, they receive NBT data of " tag: {} " and will only stack with other items that have this tag.
Items put through the furnaces will also have the tag: {} added.
The recipe book is not able to automatically place items in the grid when they have the tag: {} (see #1067 )

Versions:

Forge 40.1.0
MC 1.18.2
alexsmobs-1.18.1