It’s quite possible this diacetyl problem was caused from stressed yeast. You made the comment before that you don’t aerate your beers. Proper oxygen levels can reduce VDK by helping the health of the yeast. Consistency starts with making sure the conditions are right to achieve your objective.
Like I mentioned before, the only people who debate whether proper aeration is important to yeast health and quality beer are homebrewers.
The wort picks up oxygen as it runs out of the boil kettle.
And, our yeast is highly oxygenated prior to pitching. So much so that it will actually erupt at times, much like a volcano.
A 10 gallon split batch is in the works now, two different yeasts. Diamond (harvested many generations) and a new W-2124. Very anxious to get the results on these two.
I wondered if I rushed this particular beer. Brewed on 3-23-22, transferred to the keg on 4-5-22. OG = 1.050, FG = 1.012.
The yeast that was pitched to "fix" the beer was the same yeast that was harvested from it.