I've owned more than ten trucks over the years, a mix of spray and drop-in liners. I've never had any issues with rust with using a drop-in. With that said, I do remove my drop-ins every year to clean under them and touch up any scruffs/scratches.
I just purchased a 2025 Ranger that didn't have a bedliner. I got quotes from $550-$600 from local companies to do Rhino spray liner. I thought that was super high for such a small bed. Even the Ford Ranger 2024-2025 Modular Bedliner is listed at $495. I found this DuraLiner for just $242...