Sounds to me like the pump is just under performing - that pump is definitely capable of more throughput , even with 1/2in plumbing
Not sure if you saw my previous response, but just in case you didn't, make sure the pump isn't somehow set to underperform as part of a calibration.
Find it in your dashboard and click it. Then locate the Speed Adjust button, and make sure the sliders are set to 1% and 100%
Maybe they are adjusted to sometime lower than 100% - if not, then at a minimum , you can then rule that out as the issue