Using PHP mail() is unauthenticated.
You are best to use a library like PHPMailer which has support for authentication to log into the mailbox to send mail as that mail address.
3 other things are either missing or not properly configured.
1. Enable DKIM
Email Accounts > Enable DKIM
2. SPF...
This is a limit imposed by the ACME Provider. All that can be done is switching ACME Provider between Lets Encrypt or ZeroSSL, waiting for the rate limit to reset, or using sites like sslforfree to generate a certificate and install it manually.
Error message when you try to issue a new ssl certificate yourself?
If you are getting a message about weekly rate limit, it is not solvable aside from waiting or going to site like sslforfree, generating one and then manually install it.
Your whole website shows error 500 currently across the board, even I get error 500 visiting your site. That needs to be fixed above all else.
the search console error is not hosting issue
the websites you claim to have are multiple accounts which is a violation of terms of service, one...
500 means an issue with the php script you have.
Your whole website shows error 500 currently.
Google always has an issue on sitemap, that's a Google Search Console issue.
No one can override the rate limit. It is imposed by the ACME Provider themselves. All that can be done is to change the ACME Provider to ZeroSSL in settings or use sslforfree website to generate one and manually install it.
You are accessing the account panel via the IP Address of a VPN Provider. VPN needs to be disabled.
The error code provided affirms the fact of a VPN or Corporate Network which is not allowed.
This is not a certificate being revoked. It means it expired.
You need to get a new one issued through hosting control panel Account Manager > SSL Certificates > Get automatic certificate from ACME Provider.