I actually agree with you that the article sounds click-baity, unfortunately, HBO has made it so much harder to get good information regarding Chernobyl on the Internet nowadays[0].

Just one of four reactors "melted down". I'm no expert, but I imagine the worst possible is all four reactors literally exploding simultaneously, or one after the other in a rapid chain reaction, or something like that.

[0]: https://www.forbes.com/sites/michaelshellenberger/2019/05/09...