I’m from the US and English is my native language. I took French in high school and minored in it in college and was actually pretty fluent in it for a while. A decade after graduating I married a native French speaker from Quebec, but our semiannual trips to Quebec to visit her parents now remind me just how much fluency I’ve lost. I’m still fine in common daily tasks but get into a deeper conversation and I start floundering.
I used to work in a technical role at a Spanish-language TV station and picked up some, but that’s also disappearing now ten years on.
I guess it’s a use it or lose it situation.
Long ago Usenet and BBS networks worked in a manner that we could describe as federated, if you mean a decentralized system where servers could communicate with each other. I saw something a few months ago about a modern service that sounds kind of similar, but I don’t remember the name now. It seemed interesting but I put it in the back burner and then lost it.