See video example here:

(I have a weird Test World, I know)

Tested with ONLY Durability Overhaul and Architectury installed. When removing Durability Overhaul but keeping Architectury, the problem stops, although previously broken stacks still won't merge right; the problem just stops being replicatable until Durability Overhaul is reinstalled.

NOTE: To Replicate, make sure you're highlighting the first slot an item will drop to on your hotbar. Somehow that causes the issue. In my video example, I'm highlighting slot 2, which is where the first Glowstone go to, and after that all of them stack into slot 3 instead, and all from slot 2 become incompatible.

I can confirm that this is also happening on the Fabric version as well. I don't have video evidence right now but it is indeed happening. I've tested this in an isolated environment with only the essential mods needed (Architectury and DO 1.10.0).