A Linkedin account was made using my professional alias and personal domain

Yesterday I got an email for a one time passcode to verify an email for a linkedin account.

I didn't get this on any of my emails I use for work, but on my personal website. I have my professional alias as alias.dev (for illustration), and the linkedin account was made as alias75@alias.dev. I have a normal linkedin account, in my real name, with a different email.

This isn't somebody signing up with a leaked email – I would never use this for an account, why would I put numbers in an email when I own all the emails associated with my domain.

After a couple routine emails from Linkedin (suggesting connections for this new account) I logged into this linkedin account by resetting password. It was registered in Ecuador and the email was unverified, seems to me they don't have access to my email.

The way they seemingly invented a new email with my fake name and numbers, with my domain, seems to me that a human did it.

But why? Any reason why somebody would make an account with my fake details?

And most importantly, what should I do to lock down any potential security leaks? Although you don't need email access to make a new account.

Any light that could be shed on a strange situation would be appreciated.