User session gets changed automatically, not asking for even credentials

I am facing one issue where the case is, I logged in as my user and someone who does not have my credentials to log in but still when he/she open the link frappe is not asking for credentials and they got logged in with my user automatically.

Even sometimes if they logged in as themselves and they refreshes the page once their session is expired at that time also user is getting changed as a different user.

I also tried to replicate it but it is not happening all the time.

Can anyone have some ideas why it is happening and if yes how to fix it?

Hi @saurabh6790, above Manish has described the issue we are currently facing. Could you please help us with your inputs here.