No, that is because of the size of your emitters.
At the flow temperature you are running, at the lowest flow rate, that is all the heat they can deliver to your property.
If your emitters were bigger and your heat loss was higher, the dT would go to what you have set, that is 5c on fan coils in your case?
Once the dT is at 5c (if that is what you have set) if it starts increasing the flow rate will increase delivering more heat.
Daikin focus on return temperature.
If you set a flow temperature of say 32c with a dT of 5c, the heat pump will try and keep the return temperature at 27c.
It will lower the flow rate until that is achieved.
In your case, the flow rate won’t go low enough to get to the requested dT all of the time.
If you want a higher flow rate then you need to set a lower dT.
But then you will find that it is not very good at holding a steady flow rate.
My experience is that the flow rate is only steady if you set the dT to an extreme which either forces it to run at minimum or maximum flow rate.
Anything in between that and it can’t do it.
Then you end up with a hunting flow rate on top of the hunting flow temperature and electrical input.
All this is inefficient and I can observe my efficiency improving as it becomes more stable.
The hunting flow temperature and electrical inpt knocks a fair bit off the COP.
My experience is that the Madoka and modulation just make it worse.
So, I don’t use them, I am not suggesting you don’t, but with all that going on nothing is fixed and looking at the data it’s just all over the place.