Twitter has seen thousands of layoffs, departures, and resignations since Elon Musk took over, but one of the latest staffing changes appears to have been personal — the company’s new CEO tweeted that Eric Frohnhoefer, an employee who had publicly argued with him on the platform, had been fired.

The saga started on Sunday, when Musk tweeted an apology for Twitter being slow in “many countries” and implied that the poor performance is because the app does over 1,000 “poorly batched” remote procedure calls to load the home timeline — basically saying the app has to reach out to other servers a bunch of times and wait for a response for each request. Frohnhoefer, who tweeted that he’s spent six years working on Twitter for Android, quote retweeted Musk’s statement saying it was incorrect. Musk has done the same thing several times in response to news stories about his companies, but unlike those instances, Frohnhoefer actually went on to provide an explanation for why he thought his boss’s tweet was incorrect.

According to Frohnhoefer, Twitter actually makes zero remote procedure calls, or RPCs. Instead, he says, when the app starts up, it makes around 20 background requests. Seemingly to clarify his original tweet, Musk then responded, “The fact that you don’t realize that there are up to 1200 ‘microservices’ being called when someone uses the Twitter app is not great.” Frohnhoefer disagreed again, tweeting that the “number required to generate the home timeline is closer to 200 than 1200.”

The conversation between Musk and Frohnhoefer is messy, spread over many threads and hours (which Twitter ironically makes difficult to see and follow). At one point, Musk asked Frohnhoefer what he had personally done to fix Twitter being slow on Android — though remember that the conversation started with Musk’s apology for it being slow in “many countries” — not on Android. But Musk’s seemingly final word on it came in response to a discussion on whether Frohnhoefer should’ve brought his concerns about the original tweet up in private on Slack rather than publicly calling Musk out. A commenter in the thread said that Musk probably doesn’t want Frohnhoefer on his team after the developer tweeted that Musk should’ve asked questions about the slowness issues privately, to which Musk replied, “He’s fired.”

Frohnhoefer didn’t immediately respond to The Verge’s request for comment on whether he’d been contacted by Twitter’s HR team or had heard any word other than Musk’s tweet. (It is worth noting that if you have a public spat with Musk, your DMs, email, and mentions will generally turn into a mess.) He told Forbes that it took Twitter around five hours to lock him out of his company computer, but that he hadn’t heard any formal information about his firing from the company.

We’ve also tweeted at Musk for comment, as Twitter no longer has a communications department.

Musk has received pushback from others about his tweet, including from other Twitter employees. Sasha Solomon, who identifies herself as a Twitter tech lead, quote retweeted it, saying, “You did not just layoff almost all of infra and then make some sassy remark about how we do batching.” She also accused Musk of not learning about how GraphQL works and not knowing how Twitter’s infrastructure works.

On Monday evening, Solomon tweeted “lol just got fired for shitposting.” Her thread doesn’t mention whether she was fired by Musk directly, and he doesn’t appear to have responded to her tweets criticizing him like he did with Frohnhoefer.

Commenters outside the company have also called the tweet into question. Musk says he got the info about the RPCs from several Twitter engineers and said that “the ex-employee is wrong.”

If Musk was indeed wrong about how Twitter operates, it wouldn’t be the first time. On Sunday, he tweeted that the site is the “biggest click driver on the Internet by far,” a statement that was immediately dunked on by almost everyone who owns a website and knows how powerful Google and Facebook are. Twitter users also used Birdwatch, a feature that lets you point out misinformation on the site, to correct Musk. (It was also not the first time he’d been Birdwatched — there’s also a correction note under his tweet about the price of insulin.) He later deleted the tweet.

As for the fallout of the spat, Musk has announced that at least one feature, the labels saying which device or app a tweet was posted from, will be cut in the name of performance. So far, Musk hasn’t replied to the other suggestions Frohnhoefer made about improving performance, which include cutting down on unnecessary features and reworking systems that are holding the app back.

As for Frohnhoefer himself, he’s tweeted that it was “definitely stupid” to confront Musk the way he did, though he doesn’t seem too concerned about being fired. He’s already been encouraged to apply for jobs at other companies.

Update November 14th, 7:13PM ET: Added info about Frohnhoefer not having been contacted by Twitter’s HR team since being fired.

Update November 14th, 7:51PM ET: Added news that another person who had criticized Musk was fired.