Bug – why are outlines not aligning with fill?

Illustrator 25.3.1

Macbook Pro 16 2020

I've seen this a few times – see attachced picture. The blue box outline isn't aligning with the actual fill colour. Really annoying. I guess it's something others have had problems with?

Any idea how to fix this/why is it happening? Adobe products seem to be getting worse and worse.

Thanks.