There is a lot of pressure when your slide makes contact with the sidewall. I would suspect you either have a cable system or an electric “Rack”.
In the cable system the motor is above the slide, in the center and pulls cables to make the slide operate. That type doesn’t have a “stop” built in that I’m aware of, and depend on the operator to let go of the button at the end of travel.
The electric “rack” system has a ratcheting action the “clicks” at the end of motion. Over extending is usually associated with taking the facia “horseshoe” off and extending the room past the wall for repairs.
My wild guess is you have the cable system and either you or the previous owner has held the button too long when extending the slide, causing extra pressure on the facia (horseshoe) and the sidewall, the facia will give up first.
Hope this explains it, as I am guessing without being there to actually see and assess. You can pry off the trim and reinstall the screw.
2012 Copper Canyon 273FWRET being towed by a 1994 Ford F350 CC,LB,Dually diesel.
Airlift 5000 bags, Prodigy brake control, 5 gauges on the pillar.Used to tow a '97 Jayco 323RKS.
Now an RVIA registered tech. Retired from Law enforcement in 2008 after 25+ yrs.