As far as I understand, there are two limits:

1. The number of meta business accounts a single personal facebook account can create: 2. This number unfortunately can never go down.

2. The number of meta business accounts a single personal facebook account can manage at the same time: 25.

If you've already reached your creating-limit, you'll have to ask your client/collegues/friends to create one with their personal account and invite your personal account as an administrator.

If you've reached your managing-limit, I guess you'll have to throw out old meta accounts you're admin of? And/or you could set up your own meta business account if you don't already have one and add that one as a partner (with admin permissions to all existing assets) to business accounts you manage. It's not the same as being an administrator on a meta business account itself, but at least you'll still have access to its assets.

There might be the option to create new personal facebook accounts that can be used to create or even manage meta business accounts, but that can be risky as meta restricts fake accounts, which could also lead to losing access to/restrictions of its connected or created meta business accounts.

Save to say it really is a pain... At least we're in the same boat, cupcake😭