Right earbud gets muffled

I mostly use my earbuds for phone calls. Usually, I will just use the right earbud, as I work from home and am on and off the phone all day.

Most of the time, people say I sound good, but periodically people will say I sound very muffled and they cannot hear me.  If I pull the left earbud out of the case and use both, the sound improves.  Then after that call I put both buds back in the case, close the case, reopen the case, and then I can use the right bud alone again.

Is there a setting that might prevent this?  I am using an iPhone 14.

Thanks,

Larry in Virginia