We’ve archived the experimental-usercard repository, and don’t intend to update the theme component any further. So I’m afraid you will need to disable it before template overrides are blocked in June 2025.
We do hope to incorporate some of the experiment into core at some point, but don’t have a specific timeline on that. The user-card is a very heavily-customized part of the UI, so landing large changes to it will require careful planning and changes across the ecosystem.