My right AirPod is muffled while the left is running perfectly fine.

I've been using these AirPods for about 6 months, I may be wrong, but it's around there. This isn't the first time it's happened and it's happened to both AirPods. Separately and together. They have been cleaned and I'm not sure what could be causing this but maybe it's something to do with my phone, I have an Android and I'm unable to use or buy an Apple device to try and connect them to. It's not muffled muffled but it's like when you put your hands over your ears or something. It's really difficult for me to explain but in short one side is quieter and sometimes it switches. I don't know how it's caused or how I can reproduce it, it just happens. I'm not sure what to do. I've unpaired them from my phone and paired them again but nothing changed, I've connected them to another device and played with the volume and sound settings but nothing has changed. Conveniently enough, whenever the right one isn't in my ear it appears to be working fine and playing just as loud as the left side but the moment I put it in it goes back to being quiet. This isn't an issue of my ears because I can put the left AirPod in my right ear and there's no volume change, it's just as loud. Same with the right AirPod, I put it in my left ear and it's still quiet. Maybe it's because they're gen 1 but I'm unsure. What do I do about this?