Exactly. I’ve mostly converted, but have a few places where every LED I’ve tried flickers. So those stay incandescent.
And LED 3-way bulbs are a hit and miss affair.
Had an outside motion light that burned out incandescent bulbs after a few months. Switched to LEDs and had somewhat better bulb life but still had to change it more than I liked. Read here about getting a dimmable LED bulb and that did the trick. Bulb has been OK for a couple of years now. LEDs have sure helped with my power bill.
If you’re so inclined, try a bulb from a different manufacturer. Maybe try a slightly more ones from a better-known brand (they’ll cost more, but you’ll still save it back on power savings, if it’s a frequently used fixture).
Cheaply-made and/or poorly-designed power supplies inside CFLs and LED bulbs can exacerbate flickering.
I'd say its likely those places are on dimmers. I have a few circuits where the LEDs flicker at low settings, which I've been meaning to replace with so-called "LED compatible" dimmers.