(I'm not sure if I should include the version that the PS5 was using but I did anyway.)

I'm playing on a world with someone. They're playing on PS5 while I'm playing on Windows PC. The world is hosted by them. We have keep inventory on so there would not have been an issue with losing my inventory.

We traveled a few thousand blocks out and as we started traveling back I looked down and my entire inventory had disappeared mid boat ride. I hadn't died between the last time I had checked my inventory (it was completely full about five minutes prior) and then. We reloaded the file multiple times, I checked the area where I had been, even waited several days.

I still have all my levels and I reload in the same spot I left the game in. The PS5 player was unaffected.