Hello there,
I hope you are doing well.
We highly recommend you not to use any templates on Joomla 4 right now. Helix Ultimate 2.0.0 is compatible with Joomla 4, the templates based on the framework will also be compatible within a few more days as well, for now those are not.
If you have an existing site, please do not update to Joomla 4 now. If you want to build fresh new site, you can use Helix Ultimate 2.0.0 on Joomla 4 but not any other templates for the time being before those are compatible with the latest version.
Thanks!