It’s a good number of phones and the gist of the article is if you have old phones that aren’t being charged, there is a real possibility of catastrophic failure, which is pretty standard for batteries of any kind, particularly lithium’s.
I actually experienced this some 18635 batteries I use for my high powered flashlights.
some had swelled.
Tossed me and got new ones.
The issue seems to be how often they are used and charged.