Skin usually becomes more reactive with age, and the reason is mechanical rather than mysterious. The barrier — the lipid-rich outer layer that keeps water in and irritants out — thins and holds less moisture. A compromised barrier lets more of what you put on through, and a face that tolerated everything at 30 can sting at 60 from a product that has not changed.
The practical consequence is that ingredient count matters more than ingredient quality. Every additional component is another thing that could be the problem, and a shorter list makes a reaction identifiable. This is also why so much sensitive-skin advice points toward mineral formulas: zinc oxide and titanium dioxide sit on the surface rather than being absorbed, and the formulas built around them tend to be short.
The first thing to remove is fragrance, including the natural kind. Essential oils are fragrance; lavender, citrus and mint are among the more common irritants in cosmetics, and they appear frequently in products marketed as gentle. Then drying alcohols high in the list, which strip an already thin barrier, and then longwear film formers, which are designed to adhere hard and can be a problem on reactive skin as well as a problem in a crease.
One boundary to state plainly: this page is about product selection, not about skin conditions. If your skin is persistently red, itchy, flaking or burning, that is a conversation with a doctor or a dermatologist, not a foundation decision. If you have diagnosed rosacea, the rosacea page deals specifically with color correction and triggers.