There are generally two causes for this problem: either it is due to the LED bulb or it is due to the electrical installation.
This is very easy to check. Turn off the light switch and remove the bulb from the socket. If the LED lamp continues to glow dimly when removed, the cause is the luminescent layer used or the LED driver. These two components can store energy and keep the LED lamp lit for some time. If the light goes out immediately, the cause is not the LED lamp but the electrical installation.
If the electrical installation is the cause, it may be due to the type of light switch or dimmer. An incorrectly connected switch or an unfavorable cable routing can also be responsible for the glow. If a LED lamp flashes continuously or glows weakly, this does not immediately mean that the LED lamp consumes more power, as it continues to glow. In this case, it may also be due to the cables, as these can couple part of the energy and then pass it on to the light source. This then causes the LED lamp to glow. This process could not be observed with the previous incandescent lamp, since an incandescent lamp requires much more voltage to glow. An LED lamp can already cope with very little current and very low voltages. If even a minimal voltage is present, it will glow. So in this case, the visibility problem is only with the sensitive LED lamp. However, this problem can also occur with inferior LEDs.
Dimmable LEDs glow, while non-dimmable LED lamps only ever flash briefly and then go out again. In both cases, the voltage applied is minimal.