On my survival world, chunks are disappearing (destroying parts of my builds) and new chunks are spawning.

I have been having trouble with my world lately. In the last couple of days when I logged on to my Minecraft Bedrock edition world, I found out that many of the chunks in my world have been relocated, removed, or new chunks have replaced the old ones, destroying a part of my first ever base, and leaving a giant hole in the middle of the ocean and river. This is stressful and frustrating and to some people, this wouldn't be a big deal, but I love to play Minecraft, and hours of work are disappearing. The removed chunks have taken a part of a bridge I built in the sky, put a new island in the middle of the ocean (also removing part of my ocean bridge), spawned a new river, and I have also discovered (only two so far, but maybe more) that are holes where entire chunks should be (that lead into the void). I have played on this world for years it this is very upsetting. I have attached screenshots of the two missing chunks, as well as the new (and unwanted) island in the ocean and the part of my first base ( the image with the chests and trapdoors. that missing section also took away a landbridge and the other half of the mountain that completed the base), and the new river.