I run a fairly tight ship with regard to keeping my PC tidy, with Defender always kept up to date, regular use of CCleaner, automatic backups using Backblaze and careful on downloading software.
Over the last 24 hours I've had a couple of unexplained l o n g pauses in operation when everything's just 'hung'.
So I got Malwarebytes and adwcleaner on the job and between them they found 21 nasties - nothing serious - just bits of junk that shouldn't have been there: mainly PUPs.
I was surprised to note that I'd not rub Malwarebytes for some time... note to self: include it in your weekly housekeeping...
Of course, everyone else here does regular backups and has all their nasties-checking up to date and runs it regularly... Don't they