The SEA challengers format is unique in how it separates each nation (excepting MY/SG) into its own qualification tournament. Oddly, the RIOT import ruling still applies - teams must have at least three players from the nation whose qualifier they are competing in. This is probably due to broadcast languages.
Do you think this makes a big difference? Would SEA teams perform better given the chance to use players from many different (SEA) nations? Personally, I think this should be changed going into 2022. There's a lot of talent in SEA (Jingg, PTC, and more) that may be able to make a big impact on the same team.