As we discussed in the Brazilian forum, I suspect (but I have no evidences) that you may be right and in fact this router may have the additional amplifiers. However I believe the TX power might be reduced by the firmware due to regulatory issues. There are some reports of the russian version running a debug firmware which greatly increases the singal range.
I tested the wifi range with a laptop (with a Wifi 6E card - Intel AX210), an iPhone 11 and an iPad (on the laptop with Windows 10 I used the command "netsh wlan show interface" to monitor the signal strength and connection speed plus IPERF3 to test the troughput).
Other 802.11ac access points (TP-Link Archer AC2300 with stock firmware and Archer C7 v4 running OpenWRT) installed in the exact same location as the AX3 have a significant better 5GHz coverage.