@jqubed@llamacoffee That's my opinion, too. Arianespace updated them with a further delayed launch date (commercially confidential). EUMETSAT decided to call SpaceX.
That's the big unsolved question. Easiest answer is that they are using preburner exhaust to pressurize the tanks, but putting CO₂, CO, water vapor and maybe a trace of unburned methane into an oxygen tank sounds like such a bad idea - but like you, I can't think of anything else that could block the filters.