Run watts power & Apple health changes valid?

So, I’m kind of curious about this. I have been more sedentary this year but the run power things seems really odd. If I understand correctly this is saying my run power has been cut it half. But it hasn’t. My run paces are slower but we’re talking going from say a 7:15 mile to 7:45 mile. Nowhere near how dramatic this seems. What could be causing this “wattage” stat to change this much and could it be affecting my other markers ?