SELECT button is triggered by pushing down on the lower baseplate

I just recently got out my 3DS that I haven't used in years and decided to mod it. After using it for a while I noticed that during gameplay the pause menu in some games would come up randomly.

During some troubleshooting I found out that pressing down on any part of the lower baseplate of the 3DS causes the SELECT button to be triggered and the closer you get to the right side of the 3DS (where the SELECT button is) the easier it is to unintentionally trigger it. Also, the physical button is not moving just to inform you.

I originally intended to disassemble the 3DS to just clean it but now it seems I might have to do some investigating as well.

Posting this here as a precaution to see if anyone know what is causing this before opening the 3DS up myself.