Big problems with WP 5.8 & Site Origin North

I really like the plugin (hence the 4 stars) but it breaks two things for me. My mobile menu dropdown gets disabled, and it causes a “critical error” when someone tries to make a comment. I turned the plugin off and both errors stopped, turned it on again and they broke again, so I’m sure this is the root cause.

I’m running with WordPress 5.8 and my theme is Site Origin North. Not sure whether it’s the version of WordPress or my theme (or both?) in combination with WP Githuber MD but it’s unusable for me.