Also there are a lot of sites that can give the same sort of eye numbers as Twitter that are far better run and lower risk from the advertisers point of view.
If Twitter was a TV station in terms of ads, it used to be C5 or possibly Sky 1 (not top market for the advertisers but certainly high up), it's now heading past Bravo and Scyfi channel to GBN or whatever it's called, with about the same credibility for the advertisers.
Twitter used to get a lot of it's advertising due to the relationship between the ad teams that Musk sacked, and the buyers, with the ad team staff being known to the buyers which made the advertisers willing to throw a bit more money at twitter than they might otherwise have done, especially if there was any controversy as if the people they talked to said that twitter was dealing with/had a plan to deal with an issue it could be trusted.
When musk got rid of those people, and basically the entire department he not only lost the "human" element that had been there with the advertisers, but anyone the advertisers had learned to trust, which given everything else musk was doing would have had a much worse effect than normal (especially when those advertisers found the tools they used were broken by musk, and they had no way to get a response when they tried to report that their advertising money was being spent on things like an old campaign that had reactivated without them instructing it to, and no way of turning it off).
It takes a lot of smaller advertisers to make up for the lost money from any one of the large accounts, and tucker was toxic enough before Fox "let him go" that some of the biggest accounts actively refused to place an advert in his show.
Mind you if it turns out musk is paying him a lot it could be funny, if only for it being more money being burned up.