Actually, some studies allege that more than 4 million bitcoins are lost forever. More Bitcoins will be lost in the future. This is due to a variety of reasons such as the death of the wallet owner, lost private keys, burning coins...
What you should know is that it doesn't really matter. Satoshi answered those concerns 10 years ago:
Eventually at most only 21 million coins for 6.8 billion people in the world if it really gets huge.
But don't worry, there are another 6 decimal places that aren't shown, for a total of 8 decimal places internally. It shows 1.00 but internally it's 1.00000000. If there's massive deflation in the future, the software could show more decimal places.
and
Those coins can never be recovered, and the total circulation is less. Since the effective circulation is reduced, all the remaining coins are worth slightly more.