If you can't see other players public lobbies, then your firebase database is not set correctly:
1- please watch the video i sent again, and make sure you did every single step including the step where we add " " in the firebase config, and when you host a lobby, open your firebase database, you should see a new created document in there, if you see it, it means firebase is working perfectly, and it should be visible in the public lobbies in-game.
NOTE: In the video, when you get to the part where i create a new collection and called it "Leaderboard",here at this part, create a collection and call it "PrivateLobbies" and another collection and call it "PublicLobbies" (so dont create a collection with the name Leaderboard, no need for that one).
2- If Firebase is blocked in your country, try and open a VPN then play the game and see if the problem is gone.
3- Make sure you added the ICE server to the project (the comments at the very top shows you how to do that).