Unpopular opinion: Scrap Brain Act 3 is actually genius for a final stage. Y'all Eggmanland fans should be raving about this stage too :P
I understand how disappointing it is that it's a Labyrinth Zone palette swap, but... think about it. Of course the last level will be the same as the most infuriating level you faced so far. Who is the biggest troll: Eggman or the devs? :P
Also think of the implications! Eggman built Scrap Brain on top of Labyrinth Zone and polluted at least part of it! The main defining feature of Classic Eggman: polluting shit! We had a glimpse of it in Act 1, and here it is again in Act 3, anticipating Tidal Tempest Bad Future by 2 years - except this is not the future, it's happening right now :)
Also also! The fact that they bothered to create a completely separate object for the bubbles? So that they'd take 10 seconds to spawn? That's evil, man. That's evil. Could it be a result of Eggman's pollution? And this is why you should stop him :P
Also also also! There is a (in retrospect) fairly obvious shortcut if you want to win with the least amount of effort! A prize for the expert player! That's so cool! I love how many shortcuts Sonic 1 level have, it's a very underrated feature of its level design.
Anyway, S1 good, go play it :P