Comparing the version before the latest version of Firebase Web it looks like the FirebaseNotifyEvent in the old version was calling a REST API and the new version is running Javascript. This could be the reason that the Service Actions and Timers are not able to notify because they are not able to run javascript since they are not being called from a screen?

Just reverted back to the previous version and now the FirebaseNotifyEvent is working when I call my Service Action / Timer

This is also a problem for us...

Can you add the REST API function to this application.
Because we want to send triggers when serveractions are executed and the clients needs to be updated.

Going back to the old version will not help because the clientsecret way of authenticating is deprecated and will be removed soon. So we need to use the newer function with a serviceaccount (email)and service account private key for example. I hope you can add this because if we are only able to execute notifyevents on a javascriptenabled clients we miss a lot of calls (because the server needs to push data based on entity changes etc).

Yes please include the Rest functionality. It's very useful when using BPTs or service actions to trigger firebase events.

And add a way of using it via anonymous authentication.