Hi, konrabi1
These issue were directly fixed on your site.
1st issue it caused by plg-flex-menu on J4, we already compatible and will be updated to the next version. And I updated the latest package: plg-flex-menu for you.
2nd issue, I replaced templates/curb_appeal/css/core/s5_vertex_addons-min.php
to new file (already backup your old file).
3rd issue, if this issue comes up like an image below
you are able to custom code in: /templates/curb_appeal/css/template.css
line 678 & 685 around #s5_top_sub_bar { , and #s5_top_sub_bar_inner {
Additional infor, I attached a zip file for 1st and 2nd issue below.
You kindly check again!
Regards,