Whenever my friend logs in, he receives this notification

"Change you password
A data breach on a site or app exposed your password. Chrome recommends you changing your password on lichess.org now."

Is the password leaked by some data breach caused by lichess or chrome?

No.

what no?

There was no leak or breach on Lichess. Your friend reused a password in several places (don't do that), one of which had a leak. So Chrome tells him to change the password on every site where he used that same password.

I cannot create new positions in the STUDIO section. Why?

well @ng_style that's another theme

excuse me

xDDD

#4 ok sir, thnx for clarifying ( Unfortunately, he has the same password for his bank account)