It seems a CryptoTab happened to my son's laptop. He said that his laptop suddenly slowed after installing a script or something on his laptop. It looks like the script stuff with malware cryptotab and steals the CPU power.
The laptop is very hot when I check it until I find the culprit that looks like a miner on the browser that keeps hijacking the CPU. I'm glad it didn't end up the same as yours. If ever it happens, I can repair it myself.
My son's laptop is infected with almost all viruses and malware because the majority of the scripts he uses contain malware. Usually he plays Roblox with no cryptocurrency or money involved, so I just clean it with Malwarebytes and Kaspersky.

Hackers are constantly developing new ways to exploit and victimize innocent people, so be extremely cautious about any files you download and use on your PC/laptop.