I havent had a single site not working with a plus

You don’t even need a custom domain to do this. Google, Ms and many others support aliases with a plus (+) sign in the recipient adress.

so if you got [email protected] you can freely create new aliases like [email protected], [email protected] and they will all land at [email protected]

If your address gets leaked, you can just block emails to that recipient.

I’ve done this for most of my accounts and it works great.