BuzzBall past 14 days opened

Mrs had one of those huge BuzzBalls (1.75 litres) but didn’t realise it should be drank within 14 days of opening and now refuses to drink it. I’ve taken the burden of potentially drinking it now (or throwing away). It’s coming up on 3 weeks on Saturday for which it has been refrigerated for 95% of the time, but it has been opened before.

Has anyone ever drank one past this date and is it safe to do so health-wise? Wouldn’t be bothered about the taste. Normally would just throw it away but there’s over a litre left, seems like a waste if it’s fine…