any gutenberg page builder should work: coblocks, qubely, kadense blocks.
We are working also on own page builder for Gutenberg which will be before
summer

Which plugins do you recommend for building websites with gutenberg, e.g. page templates?

Your theme is not compatible with this plugin I think

https://tabelazdrowia.pl/wp-admin/plugin-install.php?tab=plugin-information&plugin=gutentor&TB_iframe=true&width=600&height=550

After enabling it, the website stops working properly.

I currently need a page template and gutenberg block plugin that is compatible with the REHUB theme