Having said that, based on this description: yes, the manager seems weak, but as the OP themselves state, these were annoyances. Couple of pointless chat messages, badly run meetings. Annoying, but it doesn't sound like such a big deal. Esp. in a fully remote setting, where you don't have to sit next to an annoying person all day..
Also, towards the end it turns out the manager was new at the company (first 6 months), so they were probably figuring out whatever upward reporting culture Spotify has, and maybe that's why they were asking seemingly pointless estimation questions?
In any case, openly challenging the other person in a group setting and making fun of them [with a ticket], which is what happened here, is not the right thing to do (whether a peer or a manager).
Good options are: (i) have a separate 1v1 where you talk it over with the person (ii) put up with it for a while and/or (iii) switch teams (iv) switch companies, if it's that annoying.
On the flipside, firing a person for what is described in the OP seems like an overreaction. But, judging based on one side of the story is not a good idea.
Overall, I personally cannot draw any conclusions about Spotify based on this, nor do I want do :)
Also, I'm questioning whether it's a good idea to write a blog post like this. I assume the contract had NDA / other clauses that prohibit this. In many cases, those clauses are a good idea. Eg. imagine if now Spotify, with all its marketing power, were to reply to this person's claims and represent their side of the story. That would probably suck for the author here. Fortunately that will not happen.