The only action taken against your account in case of the charge failing (so not a chargeback) is tou losing access to paid stuff, whatever it may be.

If there’s a free tier, you should be reverted to that. If there isn’t , the account obviously gets suspended entirely.

Cancelling a paid account shouldn’t result in you losing access to otherwise free-tier services.

A chargeback (taking back money after you’ve used a paid service) is a whole different can of wirms, though. Which doesn’t mean you should lose free-tier access in all situations, mind you.