People should stop using it as a synonym, then. The Latin effectively means "after death", meaning its a poor synonym for "what happened wrong recently".
We are splitting hairs here probably. After reading the article it looks like the author wrote it as a look back on their relationship with bazzite. A more descriptive one could be “bazzite and me - a post mortem” or something. It doesn’t come across as a bad faith title, at least to me
language evolves over time
post mortem is even in dictionaries (meriam, oxford, american heritage) as "an analysis or review of a finished event"