I just logged in and a little window popped up after my iPad auto filled my password and said something like this password has been part of a data leak please click here to change your password.

I closed the window and logged out.

Anyone else had this?

Yes, new-ish security feature in iOS

Go to Settings>Passwords>Security Recommendations

It’s either a user/password combo from a hacked/compromised account, or a re-used password which has also been used for a compromised account. Either way, you should change the password to a new unique one which your iPad will generate for you.

https://haveibeenpwned.com/

will tell you where the breach is from.

Don’t reuse passwords.

That’s reassuring. I use an old password for here that’s not changed in yrs. just changed it. Got different passwords and 2 factor on important stuff with a newer email account. That’s not been pwned thankfully!