没有.看到 FCM 以 GCM 为核心，任何应用的 Topics 数量都没有限制.曾经有 100 万个限制，但已被删除.你可以参考这个Google 开发者博客.

Nope. Seeing that FCM has GCM as its core, there is no limit in the number of Topics for any app. There used to be a 1 million limit, but it was removed. You can refer to this Google Developers Blog for that.

此外，根据此 发布.干杯!:D

Also, when creating a Topic in FCM, it could take up to 24 hours for it to be show up in the Firebase Console, as per this post. Cheers! :D