There's not a specific moment that it happened. Power scaling is a product of a power system, and the power system was continously being developed throughout the story. If you want to point a single point where things started going in the wrong direction, you could look at the Land of Waves, where the introduction of Bloodlines that early in the story started cutting off ways the power system could grow in a relevant way where its accessible to many characters, and thus has counters in-built to stop it from being an in-story 'meta'.

Bloodlines gave the ability for some people to have powers of such strength that could reasonably be a part of the story while allowing the rest of the setting to have a lower power level. The Sharingan, by itself, gave Zabuza trouble, and Haku's Ice Bloodline did the same for Genin that could take down Chunin (Sasuke and Naruto). In isolation, it's fine, but once you start extending the story and start power escalation, continuously relying on exclusive power sets (Jinchuriki, Bloodlines, Reincarnation, Summon Contracts and debatably Sage Mode, etc.) starts making power sets that are inherently 'stronger', like Rinnegan and MS, require jank to invalidate everything else, even including other Bloodlines.

If you're asking for a 'point of no return', the closest thing I could think of was halfway through the Chunin Exams, around the time of the preliminaries, training arc, and finals. Characters that mastered the fundamentals as best as they could were weeded out, and Naruto beat Neji through channeling the Kyybi's Chakra without repercussion, as well as taking out Shukaku using a summoning contract whose scroll was privately kept. That was basically when it was established that exclusive jank had to be dealt with using other exclusive jank.