The one person I know who loudly claims to be gluten intolerant was “electrosensitive” a couple of years ago, and now has the strongest wifi in the building. Some forms of these sensitivities seem to be time limited, or go away when the person is busy and happy.
The one person I know who has been diagnosed with celiac has had nightmarish digestive/IBS-like problems for years and years and missed tons of work because they were sick all the time. If it’s celiac, it’s been obvious for a long time that something’s wrong. It’s not a minor gut-twinge or “feeling bloated” after a bagel.