Minecraft version - 1.20
Mod loader - fabric
Mod version - 1.8.4
I am using the latest version available - yes

Describe the bug
When ever i put something in my offhand when i hold a two handed weapon it deletes the items my off hand

To Reproduce
Steps to reproduce the behavior:

1. Put something in offhand
2. hold two handed weapon

Expected behavior
I should keep the item

Screenshots or video recordings

This is intended behavior.
“Two-Handed” weapon

are items deleted or dropped on the floor?

are items deleted or dropped on the floor?

deleted

mmm, this seems to be a big problem, the mod should either prevent you from using the two-handed weapon or drop the items from your off-hand

take a look in this issue, is similar to your problem:
#268