Hi Syahir,
I noticed two instances that look like bugs.
I opened my site in Edge browser on desktop and the site is loaded in mobile view (even though site is accessed via desktop). Same thing for the Graphene demo.
Secondly, an error when using Gutenberg’s Media + Text block. When I upload an image no matter what size, and put text next to it, the preview shows that the formatting is wrong – the image goes outside the content area. Switched theme and it worked fine.
Thanks.