Heltec V4 Max TX power should be 28, not 22.

[caiannello]

From variants/heltec_v4/platformio.ini :

-D LORA_TX_POWER=10 ;If it is configured as 10 here, the final output will be 22 dbm.
-D MAX_LORA_TX_POWER=22 ; Max SX1262 output

But the V4 has an amplifier providing 28 dBm max output

[OE5DRO]