As far as I understand, Bitnodes.io is essentially a one-man project (Addy Yeow).🤷
It's one of the most important information services in the Bitcoin ecosystem. At the same time, it was likely unprofitable. Yes, Addy received donations in satoshis and earned a little from advertising, but he also incurred large expenses on server maintenance and software updates.
I see a paradox here. There's a very important and unique service. It has no equal. Meanwhile, the Bitcoin community can't find the money to support it. Everyone applauds Michael Saylor ("What a great guy, Michael, he's done so much for Bitcoin"). But no one cares about Addy Yeow...
And now he's disappeared, and everyone's scratching their heads (not knowing what to do next). Because the entire industry relied on information from Bitnodes.io to operate.
In addition to what you said.
The Bitnodes website is also used for a Bitcoin node monitoring service, and estimating the size of the Bitcoin peer-to-peer network. Based on what i heard, the site started experiencing issues around March 2026, which i believe its funding, since the website domain expired on May 3, 2026, so shutdown operation close to the date of domain expiration is not a coincident.
However, the OP can use the alternative websites like bitref.com/nodes/, or newhedge.io/bitcoin/node-map