Is it an air fork? If so, it’s likely that the seal on the air piston is compromised, meaning air has snuck past it into the lowers, pressurising the lowers and blowing the dust seal out. You should check the air pressure in your fork- if the pressure is dropping this is for sure what’s happening.
Best thing to do is get it serviced. Best case it just needs some new seals. Worst case, the inner stanchion is also damaged and it needs a new CSU too.