4:38 PM PT -- The Weeknd remains extra testy with the Grammys ... he just ripped the process on social media, calling it "corrupt."
Abel says Grammys brass owe him, his fans and the music industry "transparency."
The Weeknd was faced with a tough choice -- perform the Grammys or the Super Bowl -- but hammering out a deal to do both could've cost him Grammy nominations.
Sources familiar with the situation tell us The Weeknd's team was in talks for weeks with Grammy brass, who issued the ultimatum -- us or Super Bowl LV. We're told both sides eventually came to an agreement where Abel could do both, but not without negotiations getting very testy.
Our sources say there's growing suspicion Abel's decision to perform at this year's Super Bowl cost him Grammy noms because the bitter back-and-forth talks pissed off Grammy honchos.
It's unclear why the Grammys would play such hardball in trying to exclusively book him for their airwaves. It might be fear of duplicate performances, as CBS is airing the award show AND the game one week apart in February. Still, our sources tell us Abel and co. feel the dispute might have something to do with his exclusion.
Abel wasn't the only one who fans felt got cheated this year, voicing outrage Pop Smoke, Roddy Rich and Lil Baby -- all Black hip-hop artists -- didn't receive more nominations.