Why a Sea Typhoon implies conventional British carriers

If a Sea Typhoon were built, would Britain still leave the Eurofighter program?

Probably, and the naval aircraft would require conventional catapult-equipped carriers despite sharing systems with the land version.

Building a Sea Typhoon would require Britain to pursue a naval airframe rather than remain within the historical Eurofighter outcome. The aircraft might share avionics and systems with its land-based relative, but carrier demands would change the underlying structure substantially. The comparison is the F-35C and F-35A: visually related aircraft with important differences beneath the skin. Once Britain commits to that aircraft, its next carriers must use catapults and arresting gear rather than STOVL operations.