I wish there was a button (maybe next to the upkeep tab on the UI, or as a button on the UI for that race’s population building) that could control which upkeep you wanted to stay at, even with units being queued. Starts off capped at 100, click it to artificially cap yourself at 50 (no upkeep) even if you have higher than 50 total pop cap. Click it again to move it to 80, click it again to reset it back to 100.
In the end, just a QoL change.