I measured this. The downstairs kitchen faucet is about 1.3 gallons/minute; the upstairs one is more like 1.6 gallons/minute.

No claim is made in the official product description. At https://www.amazon.com/ask/questions/Tx36UWEEXJ1H4UZ, the manufacturer claims a 0.5 GPM flow rate "when the storage tank is full." (For what it's worth, a customer also responded saying that it takes about fifteen minutes to dispense a gallon.) I discounted the manufacturer's claim because (1) Various sources claim that reverse-osmosis systems are slow; (2) The claim was made in a response to a question from a customer on Amazon, not in an official specification; and (3) The Kinetico RO system costs $2k+ and claims 0.5 GPM. It makes a big deal of how fast it is (it's even in the name). I would expect a budget system to be slower.

The manufacturer claims 0.75 GPM on its website. Consumer Reports gave it 5/5 for flow rate.

The manufacturer claims 0.5 GPM on its website. Consumer Reports gave it 4/5 for flow rate.