Hi.
2-3 ) HU 2 is built on bootstrap 5. Some things have changed there. Therefore, before switching to HU 2, you need to make sure that third-party extensions that you use are compatible with BS 5.
This applies to many components such as Tooltip, Tabs, Accordion, Dropdowns and others.
https://getbootstrap.com/docs/5.0/migration/
So the question for Joomshaper team should be: not "How to fix it?", but "Why didn't you warn that it could break?".
While it may be have been warnings. I just do not follow this.
Fix it all is rather not difficult - it is necessary to change the names of the classes and the datа attributes in the BootStrap components that are used in third-party extensions, according to the BS 5 documentation.
For example instead data-toggle="dropdown" need to use data-bs-toggle="dropdown" and ect.