Elon Musk spent the weekend further alienating Twitter users with more drastic changes to the social media giant, and he is facing a new challenge as tech nemesis Mark Zuckerberg prepares to launch a rival app this week.
Zuckerberg's Meta group, which owns Facebook, has listed a new app in stores as "Threads, an Instagram app", available for pre-order in the United States, with a message saying it is "expected" this Thursday.
The two men have clashed for years but a recent comment by a Meta executive suggesting that Twitter was not run "sanely" irked Musk, eventually leading to the two men offering each other out for a cage fight.
Since buying Twitter last year for $44 billion, Musk has fired thousands of employees and charged users $8 a month to have a blue checkmark and a "verified" account.
On the weekend, he limited the posts readers could view and decreed that nobody could look at a tweet unless they were logged in, meaning external links no longer work for many.
He said he needed to fire up extra servers just to cope with the demand as artificial intelligence (AI) companies scraped "extreme levels" of data to train their models.
But commentators have poured scorn on that idea and marketing experts say he has massively alienated both his user base and the advertisers he needs to get profits rolling.
In another move that shocked users, Twitter announced Monday that access to TweetDeck, an app that allows users to monitor several accounts at once, would be limited to verified accounts next month.
John Wihbey, an associate professor of media innovation and technology at Northeastern University, told AFP that plenty of people wanted to quit Twitter for ethical reasons after Musk took over, but he had now given them a technical reason to leave too.
And he added that Musk's decision to sack thousands of workers meant it had long been expected that the site would become "technically unusable".
- 'Remarkably bad' -
Musk has said he wants to make Twitter less reliant on advertising and boost income from subscriptions.
Yet he chose advertising specialist Linda Yaccarino as his chief executive recently, and she has spoken of going into "hand-to-hand combat" to win back advertisers.
"How do you tell Twitter advertisers that your most engaged free users potentially will never see their ads because of data caps on their usage," tweeted Justin Taylor, a former marketing executive at Twitter.
Mike Proulx, vice president at market research firm Forrester, said the weekend's chaos had been "remarkably bad" for both users and advertisers.
"Advertisers depend on reach and engagement yet Twitter is currently decimating both," he told AFP.
He said Twitter had "moved from stable to startup" and Yaccarino, who remained silent over the weekend, would struggle to restore its credibility, leaving the door open to Twitter's rivals to suck up any cash from advertisers.
- 'Open secret' -
The technical reasons Musk gave for limiting the views of users immediately brought a backlash.
Many social media users speculated that Musk had simply failed to pay the bill for his servers.
French social data analyst Florent Lefebvre said AI firms were more likely to train their models on books and media articles than social network content, which "is of much poorer quality, full of mistakes and lacking in context".
Yoel Roth, who stepped down as Twitter's head of security weeks after Musk took over, said the idea that data scraping had caused such performance problems that users needed to be forced to log in "doesn't pass the sniff test".
"Scraping was the open secret of Twitter data access," he wrote on the Bluesky social network -- another Twitter rival.
"We knew about it. It was fine."