I really doubt it was about security/maintenance burdens. Under the hood, goo.gl just uses Firebase Dynamic Links which is still supported by Google.
Edit: nevermind, I had no idea Dynamic Links is deprecated and will be shutting down.
Edit: nevermind, I had no idea Dynamic Links is deprecated and will be shutting down.
It's a really ridiculous decision though. There's not a lot that goes into a link redirection service.