My current world was created around 1.13 and is currently in 1.18.2. Over the years I've moved a world border with updates and/or to obtain resources. I moved the border again today to try find a new ice spikes biome. I'd like to note that this is the first time since 1.18.x was released. According to F3, everything past the old world border (I expanded the border radius by 7000 blocks) is ocean with the ocean structures generating, however, it's actually just a desert or mountains. All of these 7000 blocks are reading as ocean and nothing else. It's not flat, it's generating peaks and valleys like it should. Rivers are still generating like normal, but quite a few have shallow coral reefs in (which actually looks pretty cool to be honest. Adds a little bit more to rivers).

I play this on a single player realm as I bounce between desktops and play locations on a weekly basis. I have downloaded this world and played it across multiple versions. 1.17 is not effected, however, 1.18.x is. It did fix itself temporarily, but has since broken again.

Please note the biome type in each screenshot.