Apple spent $48 million on Twitter ads in Q1, making it a key revenue stream, per the Washington Post.
It is unclear whether Apple has actually removed ad spending from Twitter, and neither Apple nor Twitter immediately responded to requests for comment from Insider.
Musk outlined in a tweet that Apple had additionally "threatened to withhold Twitter from its App Store, but won't tell us why."
Shortly afterwards, Phil Schiller, a high-profile Apple executive managing the App Store, deleted his Twitter account, which had over 200,000 followers.
If Twitter is booted off the App Store, it will lose access to 1.5 billion devices around the world, Bloomberg said.