While this news article is, apparently, not trustworthy, in general, France could demand every phone sold in the country include some kind of spyware. Many sellers already add a lot of programs by default anyway, so this would be how I image it might be implemented.

Given that 7 people were recently arrested for using privacy respecting tools like the Signal messenger and Protonmail, removing that bloatware/spyware might then be cause enough to arrest you. After all, only terrorists want to have privacy, right?