Carrier vulnerability depends on the task group and scenario

Are Queen Elizabeth-class carriers too vulnerable to weapons such as the DF-21 to remain relevant?

No; vulnerability must be judged at carrier-group level and in the exercise context, and removing carriers also removes organic air defense and strike capability.

Any carrier is vulnerable when isolated or deliberately tested against the full strength of a major state. Exercises that stretch a British carrier group until it fails are useful for finding limits, but their result cannot simply be converted into an argument for deleting the capability. The exercise context matters because deliberate overmatch is designed to expose the failure point. Without carrier aviation, additional frigates would lack the organic outer-air defense and strike reach that the carrier contributes. The answer is therefore to repair force-structure assumptions rather than remove the centerpiece.