u/DonutClarinetGuy

the among us IRL Sidemen sunday was the 2nd episode and was filmed in FEBRUARY (confirmed through BTS + Behz's trim at the time)

obviously they would not be planning some sort of forfeit 4 months in advance, with Arsenal only qualifying for the champions league final at the start of May, so it really is just a coincidence that the sheets in the bed task of JJ's last Sidemen sunday were from one of Harry's big diss tracks (the crew just had to think what are the most iconic sidemen bed sheets to pick them)

We know that Inside (or a similar equivalent show) was filmed a month ago (about a week after the charity match), and JJ would obviously be hosting challenges and the final like he's done in every Inside season previously. Because this show would be going out in a few months, if JJ had decided or was thinking about leaving back then he would have spoken to the boys about not hosting episodes of the series as it would look very weird in the future after he had left the Sidemen officially, and it would also look very weird if the show releases in a few months with him hosting it because he hadn't decided to leave at the time (with the Sidemen post implying that it was a very recent decision).

This means that if him quitting is real, either:

- He didn't take part in the series and so they have known about him quitting for a while (this would mean the entire group would have to completely cover up their feelings about this for the many pieces of content they filmed and events they attended between the filming of the series and his announcement video, likely including the Charity Match)
This would also mean that the cast of the show (most would not be close Sidemen friends) would know that JJ wasn't filming with one of the group's biggest projects of the year, so would know something weird was going on behind the scenes

- He has decided to quit very recently, meaning he disregarded the impact it would have on this big piece of content which points to it being because of a disagreement, which would line up with how quiet the boys have been about the situation so far and how sudden the video was

The second option is way more likely given how complex the first is, or the whole thing is some sort of forfeit
obviously this is just opinion and not fact