What happened to irelia junglee

's more efficient a Jungler because he can chase harder, snowballs harder, has stronger True Damage (with items) and can clear more efficiently early on. Plus he can dodge skillshots with Q and can become Unkitable with Ultimate.

has on-hit stun on demand, clears extremely efficiently, is harder to counter due to how he's innately tanky and very difficult to kite with how much movement he gets off of his passive and bear, forget if he wants to stick even harder or which basically makes it impossible to escape if he gets in range, has better particle effects with SG, and carries well or can farm well even when behind.

needs to go in on the enemy laner lower health than them to make use of her stun, her dash can reset but she needs to kill with it to do that, and she's more vulnerable to slows. Yi just does her job better (albeit squishier)

In bronze/silver, almost any champion is viable jungle.

It was a nonmeta pick that was endorsed by Riot with their "Dark Horses" thing they did. It kinda was a FOTM, and sometimes those die down when they don't prove to be that strong.

Really, she just needs too much early gold, and the jungle doesn't provide that for her. She is a champion that is defined by getting Triforce and then shitting on your enemy carries. In the jungle she is delayed nearly 2500 gold from getting Triforce. You can turn her into a melee dps carry by building Devourer on her and optimizing to that situation (bork, wits end, etc). And trying to carry the lategame after you finish Sated, but Irelia Top is SUPER strong midgame after she gets Triforce because of how well the item synergize with her kit. She transitions into the lategame by becoming pretty tanky without sacrificing a lot of damage. Given that the meta is now focused around midgame teamfights and objective control, Irelia in the jungle is just suboptimal when compared to her Top-Triforce build.