At least last time I donated blood in my country (Canada), you could discretely indicate “do not use” by applying a different sticker to the bag. This was done in case someone got peer pressured into donating but didn’t want to reveal something private that would have disqualified them otherwise.
I only ever got one ad in RIF, repeated in every spot. I think it was an app for organizing decks in TGCs, but as I don’t play any TGCs, I never bothered to investigate. As with every other ad on the internet, I only interacted with it by accident.