Knee pain when cycling after long gap.

I was very physically active and doing regular cardio and resistance training upto 5-6 days a week until mid 2021, following which I stopped working out due to a job change. My lifestyle became very sedentary since then and I have only started getting back into workouts this month. Since I had gained quite a bit of weight in between I was advised to start with cardio, and I began cycling on a machine (which was how I originally got into a fitness routine). However I notice that when I keep the machine on a higher resistance setting to cycle, my knees start to ache after a few minutes and the pain subsides when I slow down or lower the setting. So far I have not noted this in any other leg exercise. Please advise if it needs to be checked, or is a side effect of the long period of inactivity.