The restoration loop does still work, but yeah, it hits a hard cap pretty fast and people misremember how broken it actually was.
The issue is that once your Fortify Alchemy gear gets strong enough, the potions you make get exponentially weaker relative to the boost. Like, if you're making a potion that gives +50% alchemy and you drink it, re-equip, and make another one, that second potion is weaker because the math is working backwards on itself. It's not a straight multiplication loop - it plateaus hard after a few cycles.
What actually made the loop "ridiculously overpowered" back in the day was people combining it with other stuff. The big one being Fortify Restoration potions on top of the Alchemy gear, which would then boost your enchanting, which would boost your next set of gear, which would boost your potions again. That's the spiral people remember. But even that gets soft-capped eventually by the game's internal limits.
At level 24 you're probably just hitting the wall earlier because your base Alchemy skill is lower. If you're curious how far it actually goes, keep pushing it - you'll see it flatten out around cycle 5 or 6 max. Not useless, but definitely not the "make 1000% damage potions" thing people talk about.