What to do if the LED panel blinks when I turn off the light?

Hello. Please help me figure it out. In the toilet, I put on an 18 W LED panel and a fan with separate switching on with a two-key switch with backlight. When I turn off the light, it blinks: I emphasize that it does not flicker, but it blinks in full force as a color music with a frequency of once every 2-3 seconds. lighting. It is clear that it breaks through the backlight of the switch, because when I pull it off, it stops blinking. The bathroom has the same system, but exactly the same fixture 2, and one of the nickname flickers slightly when the switch is off. This is not critical and I will not correct it, I brought it this way for a general understanding. At the same time, in the toilet, when I paired the lamp and the fan with one key, the lamp stopped blinking when the backlight was on.

I found the “GRANITE-BZ-300-L” block, the description of which says that he should solve this problem in principle, connected it to the lamp terminal blocks in parallel, but nothing has changed - it blinks. Changed the polarity so, just in case, the same story. Please tell me how to solve this problem, leaving separate control of the light and the fan, and the backlight of the switch?

Thanks in advance. Sincerely, Valery.