Low Tx on 21.02.2: MT7621 vs RTL8822CS

I have Redmi AC2100 and a TVbox on Android with RTL8822CS onboard.
2.4G network, 20Mhz, a few meters away from each other.
Measurements were made with iPerf3 on Router and "PingTools Network Utilities" on TVbox.
Tx speeds from Router to TVbox are around 25mb
Rx speeds from TVbox to Router are around 60mb
Is there a way to speed up Tx?
Android phones under same conditions show 50mb Tx & Rx