why is this game a BO5?Both teams are already qualified,therefore the outcome of this match doesnt change anything,so why have it be a BO5 instead of a BO3?
Because the seeding for main EMEA tournament is pretty important on its own and negates his "this match doesnt change anything" point.
Why seeding is important?:
https://liquipedia.net/valorant/VALORANT_Champions_Tour/2021/EMEA/Stage_3/Challengers_Playoffs
It appears that EU teams that qualify through challengers 1 finals get automatic BYEs into upper bracket round 2. Thus, this lower final is the discriminator which team gets the BYE in upper bracket round 2 in EMEA tournament along with Acend as they have already secured that by already being in the challengers 1 finals through upper bracket.
Idk bro, you are assuming that #1 TR and #1 CIS team are also getting byes alongside with Acend and Guild/G2 winner.
But at the last stage... You know how they treated CIS. They put Gambit against FPX (#1 seed EU back then) in 1st round, meaning that Gambit was fucking #8 seed, even below all 3 Turkish teams. It might be the same right now for us, you never know. I wouldn't be surprised.
Yeah I get what you are saying, and you are right - I am not aware of an official announcement and this is an educated guess at best.
In terms of seeding, let's hope that f4u and Riot EU will have taken this sort of feedback into the account. We do have to give them credit in terms of double bracket format and stream implementation at least.