• The option to sign up for Twitter's new verification service for $7.99 has disappeared from the iOS app.
• Twitter CEO Elon Musk launched the paid verification service earlier this week.
• Twitter reinstated the "official" badge given to some accounts on Friday.
• Some users who already paid for the service say their paid-for blue checkmark has disappeared from their account.

Twitter appears to have paused its $7.99/month Blue subscription service, which allowed people to pay for a verification check mark, after users were abusing it to impersonate brands and famous people.

Twitter launched the service earlier this week in its iPhone app, allowing users to buy a checkmark that had previously been used to show that an account was verified or official. As of Friday, the iPhone app no longer shows an option to sign up for Twitter Blue.

The quick suspension of the service suggests that, at least currently, CEO Elon Musk's big plan to generate new revenue from users isn't working as expected.

The paid subscription service led to a plethora of pranksters creating imposter accounts on Twitter. It left the platform even more ripe for misinformation, and many cheaply acquired checkmarks were used to impersonate brands, politicians and celebrities with unflattering messages.

One current sales employee at Twitter said the company decided to pull back on Twitter Blue verification in response to the spate of impersonators. 

The employee, who asked to remain unnamed since they were not authorized to speak on behalf of Twitter, said one account resembling pharmaceutical giant Eli Lilly caused a serious problem when it tweeted out, "we are excited to announce insulin is free now." 

The tweet remained on the social media platform for hours before it was taken down. The real Eli Lilly account later tweeted: "We apologize to those who have been served a misleading message from a fake Lilly account."

Eli Lilly's stock price dropped sharply after the false message was posted, and so did other pharmaceutical companies including AbbVie, which was also impersonated on Twitter. At that time, major stock indices were positive, amidst a market rally.

An impersonator also pilloried Tesla, Elon Musk's electric car maker using the paid subscriber blue checkmark. An account with the handle that appeared as "@TeslaReal" wrote a flurry of disparaging tweets, one of which said, "honestly the 53% drop in stock price doesn't phase[sic] us. if there's anyone who knows about Crashing it's us."

The effect of so many changes on the Twitter platform presents a big problem for advertisers, some of which have already paused spending there.

Additionally, some users who already paid for the service said their recently acquired blue checkmarks have disappeared from their accounts.

A Twitter spokesperson was not immediately available for comment. Musk was not immediately available for comment.

The rollback of Twitter Blue verified comes at a time when Musk and Alex Spiro, who is acting as Twitters top lawyer now, are working to reassure employees, advertisers and regulators that they will comply with all laws and terms of a prior FTC consent decree.

Elon Musk wrote in a companywide email obtained by CNBC on Thursday night, "I cannot emphasize enough that Twitter will do whatever it takes to adhere to both the letter and spirit of the FTC consent decree. Anything you read to the contrary is absolutely false. The same goes for any other government regulatory matters where Twitter operates."

Spiro said in another e-mail that followed that his team had spoken with FTC regulators on Thursday and that Twitter has its "first upcoming compliance check" with the agency soon. He emphasized that Twitter itself, not "individuals who work at Twitter" would be held liable for any violations.

As NBC News previously reported, an exodus of Twitter executives since Musk took over has included the departure of the company's head of trust and safety, Yoel Roth, and chief of information security, Lea Kessner among many others involved in infrastructure, trust and safety.

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