> That site is suspect. The "radiation map" page did not seem to exist before today: https://web.archive.org/web/20220224230609/https://www.savee...

Just because it wasn't in the Archive.org's archive doesn't mean it didn't exist. Many websites are not indexed until someone links to them (shocker), and since no one really cared too much about Chernobyl until yesterday/today, it's not that weird that they (Archive.org) didn't come across the website until today.