Well it's all rumors, but if the news was good then Elon would be trumpeting it from the hilltops since his brand and the company's depends on the perception of his business acumen. He's certainly trying to do that[1] whereas the response has been lukewarm. Meanwhile, his people with direct relations to the major ad buyers are getting fired[2], and the handling of the relationships with industry groups seems poor[3].

The issue is Twitter under it's current debt burden can't afford to lose any of its advertisers. It needed to find a $1 billion of savings somewhere to keep the deal viable, and not lose any advertising revenue. Due to the acquisition that's off the board entirely due to tanking their guaranteed revenue[4] to the tune of $600-900 million, and since then Musk has done almost everything possible to drive away ongoing spend. So at this point, Twitter is in the hole to at least $600 million of revenue, bringing their minimum current loss for this year up to ~$1.5 billion. If you needed to explain one thing, it's that the massive quick firings were a desperate move to not lose money on that, but it's a false economy and Elon's being ruining any gains by continuing to make moves which seem like they're hemorrhaging even more ad-dollars.

[1] https://fortune.com/2022/11/10/advertisers-unconvinced-after...

[2] https://www.theverge.com/2022/11/18/23467324/twitter-ad-sale...

[3] https://edition.cnn.com/2022/11/01/tech/elon-musk-twitter-ad...

[4] https://www.businessinsider.com/activists-urging-brands-stop...