Couple of things:
1. They listened to us and brought back the deals and freebies forum a while back (accessible from left side link on relays page if you scroll down), and I just noticed it's now possible to create new posts there (wasn't when they first brought it back).
2. DBD codes:
KONTROLFREEK - 50k Bloodpoints, unknown expiry
STEELSERIES2024 - 50k Bloodpoints, expires in less than 24 hours
Edit: @Only4War1988 mentioned another code: AMD - 50K Bloodpoints