In reply to Marc.

I am NOW working with clients on their site.
I create NOW new sites for them.
And NOW i do not want my clients change the full site design.

I'm in the same position as you. So far, I've used the block editor for a couple of client sites and every now and then I receive an email asking me to fix a page layout because the client screwed it up while adding and deleting blocks. Thankfully, those are not very complex sites so it's not difficult for me to fix them. For the rest of my sites, I still resort to the classic editor.