Watt/resistance expierence with Bkool Smart Pro 2

Ladies and Gentlemen,
Do any of you have experience with the Bkool Smart Pro 2 trainer in respect to the wattage/resistance?
I’m using the Smart Pro 2 and the general feeling is nice when cycling in the Zwift worlds. There is a feeling that uphill wattage is indicated lower compared to zero or low degrees uphill.

However, I have started using the dedicated training sessions (Sweet Spot Training, SST) and feel the resistance of the trainer is not consistent all the time.
If I stick to the indicated wattage then it is consistent. But if I during the SST increase my wattage a lot (short sprint) then the resistance will increase when I’m back at the indicated wattage.

An example, Yesterday I did the SST (Short). First 3 sets of 2 x 5 min were done according to the listed numbers. However, in the beginning of the last set I did a sprint to pass a large group. When I returned to the indicated wattage then the resistance was increased a lot. I was able to keep up with the resistance for about 7 min but had to end the session before completion.

I do not have access to a dedicate wattmeter.

Do any of you have any experience with this or can point me at a solution keeping the current setup?

Bkool Smart Pro 2 is using latest software
Zwift is using latest software
No connection issues with internet
No connection issues between computer and Bkool Smart Pro 2

Some websites mention that Bkool can perform a remote calibration of the Smart Pro 2. I have however been unable to find any contact information or manual for the Bkool Smart Pro 2.