That does not sound plausible to me. Typically, your own computer would be behind a router that is either doing NAT or has a firewall (probably the former). Any incoming traffic would be directed to the router without any chance of reaching your computer. Whatever you saw was either outgoing traffic or incoming traffic in response to connections initiated by your own computer.
Connection attempts from the FBI? Could you specify that a bit further?
I don’t actually care about the IP address, I am just curious if a website is accessed via IPv4 or IPv6.
Firefox (I am not going to repeat the obvious ones that have been mentioned numerous times):
home assistant, freshrss (and a few related services such as rss-bridge), nitter and piped. I tried to host libregrammar, but ran out of memory.
For my phone (almost 7 years old), a thin needle to scrape out all the dust is sufficient. Pressurized air also helps.