Sonoma not responding to customised email links

I tried several methods to prevent email links going directly to Mail, trying to get them to go to Gmail instead. None worked, but now I found that when I clicked on a customised link, there was no response at all. So now I can't open email links unless I have the full email address to copy. I have tried quitting and reopening Mail, safe booting the OS, changing to Safari. None of these worked. I can now only open these addresses on my phone.