There's also a ton of companies selling "make money off your unused internet" apps which are all over tiktok and basically turn yourself into a residential proxy/sketch VPN egress node.
On top of that - lots of free tv/movie streaming stuff that also makes yourself a proxy/egress node. Sometimes you find it on tv/movie streaming devices sold online where it's already loaded on when it arrives.
For my use cases I block src IP for some period of time (minutes). I don't block large pools of IPs as the blast radius is too large. That said - there are well established shit hosters who provide multiple /24s to proxy/dirty VPN types that are generally bad.
Blocking on ja3/ja4 signals to folks exactly what you are up to. This is why bad actors doing ja3 randomization became a thing in the last few years and made ja3 matching useless.
Imo use ja3/ja4 as a signal and block on src IP. Don't show your cards. Ja4 extensions that use network vs http/tls latency is also pretty elite to identify folks proxying.
I remember in the 2000s a large-ish Telco network in the US was running ospf on an IX. A few of us on IRC did the what if? And one of us brought up the adjacency and it worked.
Same network also had all their network links in MRTG public too with no auth - if you only knew the hostname/URL you could see it all (which their staff would sometimes drop in Noc communication when linking a graph and you attempted to go there to poke around).
At my HS in the 90s students were frequently used to do stuff like this. Ex: this ravine/brush area we want to clean it out and chop some stuff down to make it a "nature center".
Similar in woodshop and metal working - doing stuff to fix the schools infra/bldg.
On top of that - lots of free tv/movie streaming stuff that also makes yourself a proxy/egress node. Sometimes you find it on tv/movie streaming devices sold online where it's already loaded on when it arrives.