In ham radio - we have a 'Q code' (abbreviation) for man-made noise: QRM (QRN is naturally occurring: thunderstorms and such). This is used mainly to refer to electrically noisy transformers, vehicles, misconfigured transmitters etc. Always been there, gets worse and/or better over time - but gotta figure out how to deal with it as part of the hobby.

When doing stuff on the internet, I've just decided to stop worrying and treat these scans like that above mentioned QRM. You can filter it a bit if you like [1], but really, a sensibly configured and maintained SSH server is as secure as it gets as far as I can see.

[1] https://alastairbarber.com/Building-Anycast-Network/#securit...