The x10 provided domains are subdomains of domains that x10 owns. Yes, that’s why Google is doing that, sometimes signing up for Google Search Console use may try to clear that up, not a full guarantee.
This limit is imposed by the ACME Provider. Only options are trying again later may have to wait a bit for the rate limit to reset. Or change ACME Provider to ZeroSSL or third party sites like sslforfree.com to get one issued.