FYI, to follow-up on that here, there are now some probably related tips posted about PTVO firmware on other CC2652P based Sonoff branded Zigbee devices from ITead in https://github.com/Koenkk/Z-Stack-firmware/issues/273 and https://github.com/Koenkk/zigbee2mqtt/issues/10282
The tip is that might be a good idea to try PTVO firmware but select the CC2652R chip type (and not CC2652P) in the PTVO firmware configurator to get firmware omage without power amplifier enabled.
It seems that at least some of the radio board modules in ITead’s newer products look to have a design flaw/limititation/flaw with missing components needed for using CC2652P with power amplifier enabled as per https://ptvo.info/custom-firmware-for-sonoff-zbmini-01minizb-and-ewelink-switch-zr-02-923/
Manually configuring the transmit power to 5 dBm or less in the firmware should probably also work?
So as a workaround to use PTVO firmware it is probably very likely that selecting CC2652R chip type in the PTVO firmware configurator will result in a working firmware image on the ITead Sonoff ZBMINI-L similar to the new Sonoff ZBMINI (01MINIZB) as both use CC2652P (CC2652 P1F) chip model and their radio modules have same design flaws/limitations/optimizations?
PS: Again, to manually flash a new firmware image to CC2652 based devices like these you need cJTAG (c/JTAG) compatible adapter like TI CC-DEVPACK-DEBUG adapter or Texas Instruments XDS110. See → https://electrolama.com/radio-docs/advanced/flash-jtag/