can anyone help with Heart Rate Zones and Max HR ?

I'm a trainer and confused with HR calculation.

My understanding from calculating the maximum heart rate is 220 - age. to calculate the training zone on an Apple Watch one need the resting heart rate and then the calculation happens through Karvenen protocol.

But when I open the setting for heart calculation on my watch, although I’m 22 years old Apple Watch, calculate this as 193 with the resting heart rate of 80. To me this is inaccurate and wrong. 220-22= 198. (198- RHR) x intensity zone like 70% + RHR= your ideal training zone.

I’m just wondering if anyone noticed the odd calculation like that.

to my understanding, my maximum heart rate as a 22 years old person should be 198 so how does Apple Watch automatically calculated and reach to this number and how can I change this manually?

where’s the 80 come from here Apple!!?