I have the same issue. The noise cancelling is really bad. It used to be great now it just plainly sucks. I noticed it recently when I was in the subway, I had the feeling the ANC is turned way down. Got home and turned on airplane cabin noise on the Apple TV and there is almost no reduction. The fit test said to adjust the AirPods or use different tips but nothing helps. I bought replacement tips cause I thought maybe the rubber tips are worn out after a few years. Same results.
I think it's either a hardware problem like dirt in the mics or a software problem like a bad firmware update or Apple secretly tuning down the ANC to save battery life. I have no solution and I am pissed about this since the AirPods were the best in ear headphones I ever owned. Now they are junk. I was considering upgrading to Beats or AirPods Max but I just don't trust Apple anymore.