Repairing underside of bed slide (roller damage)?

That looks similar to a slide failure I had a few years ago. Caused by a leak at the top corner of the slide. Only leaked when the slide was extended. We couldn't see we had a leak from the inside until we pulled the carpet back.

If the floor had water damage you're going to need a very thick plate to bandaid it together.

I pulled our slide out and replace the floor. Got a neighbor and his son to help lay it down on some long saw horses. Took 2 days to replace and re-install.