Don't use Game Changers to define your deck's bracket. Use its bracket to decide your Game Changers.
Unsurprisingly, a lot of people seem to take the bracket definitions as a sort of deckbuilding challenge; e.g. they try to make the strongest "bracket 2" deck they can by building a ton of synergies but not having any Game Changers or MLD. You will even see players in this channel saying things like "it's a bracket 2 deck but plays like a bracket 4". Now, if you understand the point of the bracket system, the last sentence there is just wrong; that is a bracket 4 deck, full stop, even if the cards it contains meet deckbuilding restriction rules for bracket 2. But it's an easy trap to fall into, which is why this mindset is so common.
I have discovered a sort of inverted approach to deckbuilding that makes it easy to avoid this trap. (This is intended for decks in the bracket 2-4 range; if it's bracket 1 or 5 you probably already know that.)
1. When you start brewing a new deck, do not include any Game Changers. 2. Continue building out the deck until you get to 85-90 cards or so. By this time you should have added the core synergy pieces, the land set, and a basic suite of ramp/removal/card draw/etc. 3. At that point, **stop building** and evaluate the power level of the deck. It can be useful to goldfish it a few times at this stage (temporarily cut some lands if needed to get the balance right). 4. Decide whether this feels like a bracket 2, bracket 3, or bracket 4 deck. 5. If you decide it feels like bracket 3 or 4, add appropriate Game Changers/MLD/combos at that point. This shouldn't require any cuts if it's bracket 3, and generally very few for bracket 4. 6. Finish out the deck to 100 cards.
By allowing power level to dictate how many Game Changers you have, you avoid having any mismatch between the power level and what deckbuilding restrictions it meets.