"These provisions could be used," said the company, "to force a company like Apple, that would never build a back door into its products, to publicly withdraw critical security features from the UK market, depriving UK users of these protections.".
There's no question that Apple will allow the UK to force it to weaken global security, so it's most likely that UK users will lose end-to-end encryption.
This means that Apple would disable end-to-end encryption for UK users rather than allow a backdoor access that could be used to spy worldwide.
During Conservative Boris Johnson's tenure as Prime Minister, the UK government claimed to be in discussions with Apple about creating a backdoor into iOS that would allow it access to all user data.
UK Parliament.
