Folks on another forum report they put a velcro strip on the bottom of the 'floppy' vinyl with corresponding strip on the floor when the slide is fully extended. When slide is extended they press it down. When it's time to bring the slide in they lift it to free it. I have not personally tried this but I am going to as my 'new to me' 5er has this problem. Not an expensive experiment.
2022 RAM 3500 Cummins SRW long bed, 2019 Open Range 319 RLS, Reese Goosebox, disk brakes