Usually the flavors containing diacetyl were the ones making the flavor more 'buttery' or freshly baked-like, so avoiding them altogether was something a lot of people were doing.
As a former vaper, if you're a vaper, please try using unflavored eliquid. Pretty much PG + VG + nicotine. You get used to it real quick, it's not that bad, you can easily tell when the coil goes bad (and the coil lasts way WAY longer) and you don't have to deal with any 'mistery' flavor ingredient. This is what ultimately got me off vaping, as I stopped being excited about the flavor and about the vice which ended up becoming a hobby. Unflavored vaping demoted vaping to what smoking used to be for me. A mundane bland meh habit which I eventually stopped. Not to say it's worse than cigarettes. It's better than cigarettes but nothing beats not inhaling foreign substances.