It is possible to be proud of being unimpressed and become easy to impress that way.

Being hard to impress looks like discernment and can be a rule you are following. Once it becomes part of how you see yourself, the reaction is decided in advance, and you are as predictable as the person who likes everything, just in the other direction. Reflexive disenchantment is not judgment, it is a different automatic response.

Try noticing something you actually admire and saying so plainly, without qualification. It is more uncomfortable than it should be, which is the tell. Enthusiasm expressed openly costs something, and that cost is part of why it is worth more than a critique.