You've successfully set up your custom domain, and it's marked as active in Event Setup. However, if you encounter errors accessing your site through the custom domain, it may be due to a conflict with your existing CAA records. If you don't have a CAA record on your DNS, then you can ignore this article.
If you have a CAA record, then to address this issue, you will need to add a new CAA record to your DNS with the following details:
Name - @
Type - CAA
Value - 0 issue "pki.goog"
TTL - 60
As usual, please also ensure that your have a TXT record based on the details displayed in the Event Setup section.
Important Things To Note:
Once the TXT records have been generated in Event Setup, you have up to 24 hours to add the DNS records and verify them. If later than that, the TXT records may have been regenerated, requiring you to add the newly updated ones to your DNS records.