Twitter has temporarily limited the number of tweets users can see in a day to avoid "extreme levels of data scraping" and "system manipulation" on the site.

What did Elon have to say?

The CEO of Tesla and SpaceX, who is also the executive chairman and CTO of Twitter, stated that the restrictions are temporary, but verified accounts will be allowed to read 8,000 posts per day, unverified accounts will be able to read 800 posts per day, and new unverified accounts will be limited to 400 posts per day.

Later in the day, Musk tweeted the limits would be raised again, “Now to 10k, 1k & 0.5k.” Musk did not specify when the limits would be abolished or enhanced. He increased the limits twice from the previous rates he had set earlier Saturday afternoon.

Nonstop user reports:

Musk's statement comes as hundreds of users experienced issues accessing Twitter on Saturday, the latest widespread outage since Musk purchased the social media network late last year.

Many users who attempted to view or submit information on Twitter's website or mobile app were faced with an error message stating that the "Rate limit has been exceeded" or that "Cannot retrieve tweets" had been reached. More than 7,300 people had reported problems with Twitter to the website 'Downdetector' as of 11 am Eastern Time.
 

An ongoing issue:

The outage on Saturday is not the first time Twitter has had technical difficulties in recent months. Users were unable to post on the site for roughly 90 minutes in February after obtaining a notification that read, "You have exceeded your daily limit for sending Tweets."

Users were temporarily unable to click on links or load photos in March. Other failures corresponded with news of a Twitter data centre closure and large layoffs, which Musk claimed were required for the company's financial health.