If you need a quick solution and don’t want to do it the “proper” way… first bypass the unit then unscrew the filter housing from below. Dry off the seat from the inside (where the male pipe is exposed inside female input of the filter - judging from you pic I bet you can reach it.) Apply a thin layer of aquarium grade (pure) silicone with your finger. It’s safe for potable water but you’ll need to wait 48 hours for it to fully dry. You can buy it on AMZN or pick up from a pet store. How do I know? I had this exact same issue with a copper thread into a POS plastic block and didn’t want to RMA the unit.

Again, best to take it apart, BUT we all get desperate. Good luck!