I would have guessed that too; however, I can’t turn it off because for GPU Lightmass, this feature must be activated compulsorily.
Sometimes there are things that don’t work as they should based on pure logic. While it’s not a bug, it’s just poor design. However, in cases like this, where no version or setting leads to a satisfactory result and it’s unmistakably evident that an option doesn’t function as intended, it can indeed be called a bug. In this case, the compression should definitely not have such a strong negative impact. If you disable compression, texture streaming should certainly not appear like that. So, if being a developer is necessary to fix these issues, it’s a bug.