Will Plugging Two Kingstons in a 2019 iMac Drop Clock?

The 2017 iMac will be downgraded when using Kingston, so I would like to ask friends who have arrived, has anyone tried the 2019 iMac mixed with Kingston memory and the frequency will be downgraded? -Why a Kingston? Because my home is in a small place, it is more convenient to buy it only on JD.com, but only Kingston is self-operated.