According to GIMPS, this is the first time a prime number was not found by an ordinary PC, but rather a “‘cloud supercomputer’ spanning 17 countries” that utilized an Nvidia A100 GPU chip to make the initial diagnosis. The primary architect of this find is Luke Durant, who worked at Nvidia as a software engineer for 11 years
There are infinite prime numbers. This has been known for thousands of years. You can find numerous proofs of this online, and go through them until one makes sense to you.
Also, quantum computers are on track to make division-based cryptography useless in the next decade or two. (Note that this only affects public key cryptography, and not shared key cryptography. So your online backups should be safe as long as you have a password for them.)