I don’t think I can “name and shame” the person here but I first played freelance trials against this person and after they lost the first two rounds, this person would just sabotage the game and jump off the map. Easy win for my team. Unfortunately, the next game they were on my team and what do you know, they did the same thing. The sad thing is we could’ve won. I’ve blocked and in-game reported them but I saved some recordings too.
You can report them in game under 'griefing'. Bungie's security team will see the report, review it and take action if needed. You don't need to submit anything else.
Also, blocking a player only blocks communications. It does not stop you from finding that player in matchmaking activities.