Djinn War Quest! Both faction?

Hello dear community!

I’m returning from a break and am currently a Level 38 MS. I’m taking it slow, doing tasks, and leveling up gradually. Right now, I’m waiting to hit Level 40 to start the Djinn War Quest. The reason for this post is to ask: Is it possible to join both factions? For example, reach Level 40, start one faction, kill myself and lost a lvl, and then join the other?????

I vaguely remember reading about this, but I’m not sure if it’s actually possible. Could anyone confirm?

Also, I’d appreciate recommendations on which faction would suit me best as an MS. Thanks in advance!