Sounds like the pre-load tension on the awning roller on that side has slipped. If you have the manual for your topper, the procedure for tightening the topper should be in there. If you don't have the paperwork, someone here might, if you have the make and model of the topper.
Otherwise the web (or your dealer) is your next stop.
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW