Being able to play games without a disk

I had a similiar experience a few weeks back.

All my disc games that is also available on Gamepass seemed to not need the disc in the drive to be able to play. Since my gamepass subscription expired i had to place the disc in the drive to be able to play the game.

I wonder if you unlink your father's account from your account would it matter?

Which games in particular are you experiencing this behavior with? Are you a Game Pass subscriber? You may be seeing games are now playable digitally if they've recently been added to that service or if as you said, your dad bought the games digitally
and your Game Sharing.

Could depend on what they are. Occasionally there are free play days so if you own a game on disc that is part of that, you can play it without the disc while those are going on. If your dad does have your console set as his Home and he owns the games
digitally, then you would have access to them as well. If you have Game Pass and some of the games were added there, that could also be the reason.

Could be what you suggested about your dad. Could be that the games went to game pass or GwG. Could be a few different things. Which games were they?