You are right the period would line up with the issue we saw. But also, I can’t help but to think even /\w+\.twitter\.com/ will match unexpected domains like f

You are right the period would line up with the issue we saw. But also, I can’t help but to think even /\w+\.twitter\.com/ will match unexpected domains like foo.twitter.com.evil.ai. I already gave you the hint it needs to be anchored!