Hi,
As for the hamburger menu icon not working, you will need this plugin to make it work.
https://github.com/tomusborne/amp-for-generatepress
As for the CLS issue, Tom provided a summary here:
https://generatepress.com/forums/topic/cls-issue-more-than-0-25-mobile/#post-1327908
It’s hard to tell how to address this when even the page performance testing site shows a CLS of 0
. And usually, these things are caused by inserted ads or lazyloaded images which are not controlled by the theme.
That said, you may be better off addressing the more obvious issues.(TTFB)