I was trying to join a warzone match but in matchmaking as soon as I joined the game it popped me into intermission, I lost boost (Warzone rp jackpot) and didn’t get any bonus RP
Did the match show up as a completed match for you? If so, then the boost was used and you would have received a set amount of RP. If the match didn’t count, then you’ll get the boost back after playing a match or restarting your game.