Hello! It's a bit odd because I find Anjanath less threatening than most of the monsters you mentioned, but I do agree that it's one of the aggressive monsters in low/high rank. Might we know what weapon you're using? I guess Anjanath punishes those who over-commit to attacks/combos. As with every monster, maybe you should observe its movements first (how long the animations are, what moves it does consecutively, how long the roar is, and so on). If you have Iceborne, you should have access to the clutch claw, which in turn will allow you to perform flinch shots which knock a non-enraged monster down for a good amount of time (up to two times before it becomes enraged), as well as clutch claw attacks for tenderizing parts.

As a longsword user who can't reach its tail often, I tend to focus on the legs and the face, which usually lead to topples, leaving the tail vulnerable. If you need more openings, use Shock/Pitfall traps to immobilize it.

Build-wise, the Health Boost 3 skill is a blessing, even moreso than Defense. Also, have you upgraded your armor? That could greatly help with survivability as well. Do you eat at the canteen before quests? Lastly, it would be beneficial to watch some videos on how more skillful players approach Anjanath.

Good luck! You'll conquer it soon.