@xmifi It just is a gut feeling.
When in a party, the one with the highest rank becomes squad leader.
When another player joins your squad, that player becomes squad leader.
Example:
You play in a party with 1 friends, and join a match, most often one of the single players becomes squad leader.
If one of your friends joins your party and then your squad, the new player in your squad becomes squad leader.
If now a third friend joins your party (4 player party now), the last player becomes squad leader.
So as almost everything in BF2042, inconsistency is key.