It may be due to cold, alergies. If not...

It's a common problem, many military diver candidates are disqualified because they have trouble clearing on the way down.

From a diver perspective, it gets easier the more you do it. Maybe the tubes stretch out? Try doing valsalva a lot, see if you can GENTLY pressurize your inner ear. Or do some skin/scuba diving.

It's common to have scarring in the tubes from childhood infections, you can also just have small tubes I think. It's possible to get plastic tubes surgically installed to keep the natural tubes open, sometimes people do that if they want to be a SEAL, etc badly enough. Probably not worth it for aviation if you are OK with routine ops.