Special type of LED bulb -- Household?e

Maybe a bulb for a dimmable switch will work.

 

There are several kinds of lighted switches. Pretty much any of the others should not do this. Look for "Lighted toggle switch" or" illuminated toggle switch". There is also a thing called a "SnapPower SwitchLight" which is not a lighted switch, it is a lighted cover plate for the switch.

 

^ That first IF you're sure that your connections are tight and right.
If the LED bulb is flashing at a consistent rate then it's a medium good bet that the problem isn't a poor electrical connection.

I have to admit that even though I've been an electronics tech for a while now I do not understand all of the ins and outs of LED lighting (automotive or home.)
Some old dimmers and illuminated switches with those old neon indicator lamps can give LED bulbs grief.

Buy a couple of different LED bulbs and see if the problem continues or exchange them with other LED bulbs in your home.
If you're like me, you have LED bulbs from more than one company.

Some light reading if you want to figure out the wonderful world of pulse modulation dimming, LED forward biasing, neon indicating lamps, etc....

Light Emitting Diode or the LED Tutorial
Neon lamp - Wikipedia

Me?
I try to keep things simple.
I tried to put a fancy timer switch in an outdoor circuit about 10 years ago, and the LED bulbs outside our humble home lost their minds.

My sweet CFO 'shared her thinking' with me on the matter and I replaced the switch with a Mk-1, Mod-0 Single Pole toggle switch without delay.

 

You'll need a different switch, unless this one was wired incorrectly in the first place.

Some illuminated switches require a circuit path through the light bulb they control: they leak a tiny bit of current through the bulb filament, and use that power to light up the switch itself. Because the current is tiny, the bulb filament never gets warm enough to glow.

LEDs don't work like that. Modern packaged LEDs include some electronics to stabilize the voltage, rectify it to DC and do a few other things.

When you put one of them on a switch like this, the switch tries to leak current through the bulb. The LED will allow it to leak through, but it also captures a little bit in a capacitor. When the capacitor eventually fills up, the LED starts up.

Normally, the capacitor keeps filling up sixty times a second and the LED stays on- but remember this is not normal operation: this is just a trickle flow of current, so instead you just get an occasional strobe.

An illuminated switch with its own neutral connection would eliminate this. It's possible your switch already had that, but the wire was not connected.

You'd run into the same issue with timers and remote-control stuffs: Whatever it is, you want the modern version that has its own neutral wire to complete the circuit for the secondary (remote, glow, timer) function.

 

For a switch to do its job as a switch, nothing more is needed than to bring one side of the light circuit to it, so the switch can break that side when you turn it off. The side that's supposed to be broken is the 'hot' side, the one that's color-coded black (or anyway not-white).

The other side of the circuit, the white "neutral" side, may or may not even be present in the switch box.

One way you can wire a switch box is to bring power into it on one cable (a black and a white), and have another cable leave the box going to the light, and you just connect the two whites together, and wire the switch between the two blacks. Neutral, white, passes through that box but isn't really used there.

Another traditional way is to just use a "switch loop" from the light; at the light, power is put on one wire of the switch loop and the other wire is connected to the light. In the switch box, only the loop cable enters the box, and the switch just connects the two wires. Standard cable is used for the loop, meaning there's still a wire that's white, but in this case it ain't neutral. The electrician is supposed to make black marks on it at both ends, but not everyone will have remembered. Strictly, the white (with black marks) in a switch loop is supposed to carry the power to the switch, and the ordinary black carries the switched power back to the light. You may encounter examples that were wired the other way.

In a switch box wired on a switch loop, the neutral side of the circuit isn't present at all.

Now, what happens when a switch has a little bitty light in it?

Somehow, a complete path is needed from the hot side of the circuit, through that light, to the neutral side.

How can they build a switch where that happens, when maybe you'll be putting it in a box where neutral isn't even available?

They used to get away with putting the little bitty light right across the switch terminals. The small current flowing through it would just flow out the switch and into your regular lighting circuit. A current that small could return to neutral right through your incandescent bulbs without lighting them up, and there you go, a switch that lights up, without needing extra wires in the box.

Trouble is, LED lights are so efficient that even the tiny current running through them from the light in the switch is enough to light them up ... or at least enough to flash them after accumulating for a few seconds, and repeat that endlessly.

In new construction, the switch box now would have neutral available in all cases (meaning cable with an extra conductor, when a switch loop is used), so you could install whatever kinds of newfangled switch gadgets you find in stores now that use power: switches with a light and an extra terminal for neutral so it doesn't have to flicker your LEDs ... switches with programmable timers ... switches with Wi-Fi ... switches that ask ChatGPT what are your favorite times to have your lights on.

But in old construction, if there isn't a neutral available in the switch box, that limits the possibilities.