The government is suggesting that it might ban some Apple security updates. Under the latest plans, tech companies would need to notify the British government before rolling out a security fix but might be refused permission if it blocks a vulnerability that’s being exploited by security services.
I believe Apple’s flat out told them that if they push these restrictions they’ll disable iMessage and other services for UK residents.
Given that the vast majority of people use whatsapp this isn’t really a big threat.