How to display a list of all tags used across different types of documents

Thanks. Could this also be the root of this unrelated issue:

I took the Prismic Starter Rails app and upgraded it from Rails 4 to 6:

And, that Prismic Start Rails app had this endpoint in config/prismic.yml:

https://bailout.cdn.prismic.io/api

If updating that to this is needed, that would explain a lot of things I found confusing about the docs:
https://bailout.cdn.prismic.io.cdn.prismic.io/api/v2