in previous seasons (the golden age of league arguably) seasons 3-4, junglers routinely had 3/5ths total gold from what their solo laners had and were usually 2 levels down from everyone else, rivaling the support maybe 1 ahead of them if they were farming a lot.

but with jungle changes.... they have more exp/gold/and less vision on the map, giving them more power to do whatever the hell they want.

junglers are supposed to be weaker than everyone else on the map

their trade off is

increased map presence, and 2v1 creation and giving your team man advantage

the jungle role was never meant at any point in time to be a powerhouse for the team, at least not without feral flare/lantern/razor and their mid game powerspike (trade off being they stayed in jungle the first 15-20minutes)

TLDR; you need to lower their total gold/exp earned across the board

((its why lee sin level 3 in the bot lane was a thing))