I got an email from Firebase saying that starting June 20, 2024 the legacy Firebase Cloud Messaging (FCM) APIs will be discontinued.
I read the document thoroughly and googled my question, but I could not come up with an alternative solution. Please assist me if anyone has any additional ideas.
firebaser here
Sorry if the message you received wasn't clear. It should contain a list of the API that will be discontinued (they were deprecated many years ago already) and the new API to call. If that somehow didn't show up correctly, you can also find the information in the FAQ on FCM features deprecated in June 2023.
I'm not going to repeat all the APIs here as its quite a list. The important thing to realize is that the versioned API was introduced years ago already, and is documented in the Firebase documentation on sending messages for example on building send requests. If you have code that still uses the legacy API, there's also a page on migrating from legacy FCM APIs to HTTP v1.
Update: due to a large number of requests, the shutdown has been moved back one month to July 20, 2024.