Text has to stand out from its background enough for everyone to read it.
Text needs ≥ 4.5:1 against its background (3:1 for large text / UI).
Grey-on-white looks refined on your monitor and disappears on a laptop outdoors. AA needs 4.5:1 for body text.
Check interactive text with a contrast tool — pale primaries are the usual culprit.
Light-grey placeholder text at 2.5:1 looks refined in the mockup and disappears on a phone screen outdoors. Raise body text to at least 4.5:1 (and large text to 3:1) and it stays readable for everyone, including the roughly 1 in 12 people with a colour-vision deficiency, for whom the “elegant” low-contrast version was never elegant at all.
Contrast minimums are floors, not targets. You almost never want to drop below them. The narrow exception is genuinely decorative, non-informational elements like a faint background texture or a disabled control's placeholder, which are exempt. But “it's just a label” usually isn't decorative. It carries meaning, so it counts.
A settings screen shipped with 'Save changes' in pale grey on white — about 1.6:1. The one control that commits the user's work is the one they can't find.