The editor basically never flushes the streaming pool. So any textures you see or inspect will get added to it, and it just gets bigger and bigger, the longer you wait before a restart.
However, the pool is managed properly in a packaged game. Not sure if that’s the case in standalone.
I see you have a lot of non-streaming mips. I’m not exactly sure what that is. It guess it could be textures you’ve set not to stream, but you’re only 20MB over in your example.