My beagle has suddenly started resource guarding random stuff. What should I do to get this behavior to stop?

I'll start off by saying that he has a bad past life. He was obviously abused by his previous owners and straight up abandoned in the woods. He has bad anxiety that he is on Prozac for, and it seems to be helping for the most part.

Lately he has been grabbing random shit and snapping and growling when someone tries to take it. He'll grab the stuff off tables and counters to chew, so it's not like he's finding random stuff on the floor.

Last night he grabbed tape off of a table and when my sister tried to take it, he bit her hand. It wasn't hard and barely left a mark, but it is still incredibly concerning. I was the victim of a severe dog attack as a child, so any aggression is not okay. I don't want to have to get rid of him because he's my baby boy and I love him so much.

I have no idea how to stop this behavior. I've never had a dog act like this. It started in August and has gotten worse in the past month because our living conditions changed. I broke my ankle/leg and I'm laid up for a while at my parents' place.

Do y'all have any suggestions?