I think I have a tendency to stay in too high of a gear because I'm still learning. But I was doing that with my old bike too?
When I was a teen and young adult, I could accelerate pretty quick from a dead stop with a fairly high gear ratio with no knee pain. But as a much older adult, I can't. If you feel yourself using a lot of muscle to pedal, then shift to a lower gear.
You do need to let your knee recover before you do any significant cycling. And if you do ride before it's recovered, then keep the load on your knees very light by using lower gear ratios than you have been.