ATTINY85 LoRa FHSS handler

I made a ATTiny85 to change the carrier frequency of a SX1276 LoRa module to relief the FHSS work load of the main MCU, a Nano 33 IoT. It is communicating with LoRa via SPI correctly, correctly responding up to the fourth channel hop according to my oscilloscope, but the communication over the air is not.
I suspected it was the hop period being too short for the slower ATTiny85 (programmed 16MHz, working at 3.3V, SPI clock measured 8MHz; vs Nano 33 IoT with hardware SPI, 48MHz). But after I change the period from 8 to 50 symbols, it's still not working.
Now I think maybe it's the speed difference between the ATTiny85 and the other device it's communicating to via LoRa.
I'd like to get some advice and know what else could I try.

Since you have the code, why not have some fun, up the t85 to 16MHz or faster at 5V.

Aight, it was a typo. I programed it at 16MHz. But it must work at 3v3