Firebase Send Message to Multiple Topics - firebase

Question

I've been trying to send cloud messages to users who subscribed to multiple topics through an API call (POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send) with the following body:
{
headers: {
'Content-Type': 'application/json',
'Authorization': `Bearer MY_ACCESS_TOKEN`
},
body: {
"message": {
"condition": "'cat' in topics || 'dog' in topics",
"notification": {
"title": "Message Title",
"body": "Message Body"
}
}
}
}
I wrote this config according to the FCM documentation. I can get a response similar to this:
{
"name": "projects/myproject-b5ae1/messages/5735743068807585451"
}
but no messages were received by any devices.
I've used the access token for other APIs, which works. I'm also aware that the FCM documentation also provided a different body for the cURL request, which I also tried but not working.
The weird thing is if I only provide one topic in the condition, a message is actually successfully sent to subscribed devices. Am I writing something wrong?
I've already referenced other solutions on Stackoverflow but everything is still not working:
Firebase API call with multiple topics in condition
How to send FCM Push Notifications to multiple topics

Answer 1

After talking to Firebase Support, they pointed out the problem I'm having here is a known bug they are still trying to fix. And there's no specific timeline for a fix yet.
Therefore, there's no problem with my code and I'll have to figure out a workaround myself if I really want to use the "||"(OR) operator.
My current workaround is keep track of subscribers with a database (since Firebase doesn't offer subscribers querying), then implement the OR condition myself by finding a union of subscribers to different topics.
P.S. I just don't get why the downvotes, I actually found a bug here and referenced all the solutions I could found on SO before asking the question here.