Best email management tool for many different addresses/domains?

I manage about 10 different email addresses from about 5 different domains and want them to be integrated in only 1 inbox.

I was using Google Workspace, but they started charging for each address.

Then I've tried Mailspring, Outlook and a few others with free plans/trials. Either they didn't have the "1 inbox" option or other issues.

I've been using Vivaldi Email for a couple of months and it's OK, but confusing/buggy for some stuff (for some reason I don't find some sent emails if they don't reply to me, I have to erase twice some emails...).

Most of my work is email-based, so I don't mind paying 10$ or 20$/month for a really good software. But I don't want to pay per address/domain (I might have even more in the future) or suffer "new" issues. Too many migrations in a few months already... 😅

Any suggestions?

P.S.: I'm using Windows and Android (although I don't really use email in my phone).