This is interesting, and made me look closely at flow rates for my setup….and compare to yours.
I saw yours was around 10L/m -ish and mine was 24L/m - yet the documentation for the Daikin 9-16kW Altherma 3M Monoblock states 28L/m as minimum flow rate for DHW recharge.
I also seemed to remember seeing ~30L/m or just over when I first got the unit and was glued to the Daikin controller (given flow rate etc. was only available there)
Just kicked off an evening DHW recharge and the pump is now holding some power back at a value of “18”, which is equates to 28.2L/m - good I guess as it normally sat at “4” (100=off , 0=max speed - however have not seen a value lower than 4)
Power mismatch? Your Mixergy pump setting might be worth testing on “2” rather than “3” for example- mine is set to “3” for reference.
More detail on my findings and partial blocked filter on the flow rather than return here: