This is definitely the best protection. If the provider drops you, you move your domain to another provider. But, as far as I know, while almost all email providers will host your personal domain, none that I know of will do it on the free plans. But your email is your identity. You should be willing to pay for it, especially if you host it on a provider that otherwise won't make any money on you.

There are a couple of downsides. If you forget, or are unable, to renew your domain, you lose it and your emails. Make sure another family member or friend can pay the renewal for you if, for some reason, you cannot.

While your own domain makes it far less likely that your email will be canceled (because you can move it), abuse of your domain can result in your losing your domain name and your email, especially before it has earned a reputation.

Which brings up another IMPORTANT point. If you use your own domain name, then you must set up your DNS records to protect your domain from spoofers and spammers so it doesn't get blacklisted or, worse, doesn't cause cancellation of your domain name. Scammers and spammers WILL try to send email using your domain name. You need to tell email clients to toss these rogue emails and give them the means to determine spoofing and unauthorized use. Read this: https://www.valimail.com/blog/dmarc-dkim-spf-explained/

Also, be aware that SpamAssassin considers .com, .net, and .org TLDs to be far safer than .world, .online, .blog, and most others. Using one of these newer TLDs results in a higher spam score, and your email is more likely to end up in the spam folder if it reaches the magic score of 5. A new age TLD can add as much as 1 point to the spam calculation depending on the email provider receiving your email.

So your own domain name is safer but costs money and requires more work.