If you have activated the Collect all in backpack function in the backpack. Then the item you are holding, for example, a weapon, a hammer... is put into the backpack when you use the removetool and activate it.

Duplicate issue, was reported 3 days ago.

https://umod.org/community/backpacks/50896-remover-tool-and-gather-function-isnt-working-well-together

Thanks