That's not super great but that's only 8/100's of a volt between all 6 cells. It would be beneficial to check the battery's internal resistance to see where that's at.
A theory I have is that all the Yuneec 920 batteries were made in only a single production run. Since Yuneec did not sell very many 920's there would have been no need for a second or more battery production run had the original run provided sufficient quantity to fulfill orders as they've come in. That original battery batch would have occurred a little over two years ago. A lithium polymer battery starts out with a natural life cycle limited in two ways, calendar age and number of charge/discharge cycles. Old age for a li-po is roughly two years and if they are handled correctly the number of useful charge cycles is generally between 200 and 300. There have been people buying new 920 batteries that are experiencing puffing in the first few cycles. We don't know how old the batteries are but they have a very low "C" rating, estimated at 8C-10C. The more demand you place on a low C rated battery the more they get beat up and the faster they age. Unfortunately we have no way to find out how old the batteries are unless Yuneec elected to share that information.
We should also expect that using the EC-3 connector has likely induced a lot more resistance than necessary with energy transfer between the battery and aircraft. More resistance, which reduces voltage, generates more heat, more heat generates a shorter battery life. The EC-3 is not a high amperage connector. It would be interesting to log the current load on a 920 during lift off and at full throttle operations. If that load exceeded 60-70 amps (I would expect it to be between 70-110) the power connectors could be quite limiting.