Summary: When I click any link in an email inside of Outlook, I get that error message. When I switch default browser back to Chrome, I do not get the error message.
Yes, it is an Outlook error message, and it only happens when Brave is the default browser. When I change the default browser to Chrome, it works fine. I changed it back, and same error message. So, I’ve come to the conclusion that the suggestions you’ve linked to don’t apply.