bad socket or bad job grouping the wires in the back, basically loose connection in the wiring. I would return it or replace it, depending on how long you have had it, it is repairable as well.

what type of bulbs is in the other fixture? Have you tried several brands of bulbs, or several bulbs of the same brand?

When you say it blinks at 10-15 seconds intervals, is it steady or intermittent? The two major causes of LED bulbs blinking or strobing are overheating or undervoltage. Make sure you are using bulbs that are dimmable, even if they are not on dimmers.

What happens if you switch the bulbs between the "good" fixture and the "bad" one?

if one socket flickers after multiple bulb changes it not the bulb. the end.

I installed two identical LED fixtures. One I wired into an existing circuit with a dimmer on it. It works, but at certain dimming levels it is somewhat intermittent. For the other one, I used a new Lutron dimmer, designed for LEDs and it works better. In both cases, they don't blink when fully on and, of course, are off when the dimmer is off. (Actually, the first one has an on-off switch in addition to the dimmer).

that's a compatibility issue not a single socket flickering. I repaired lighting for a lot of years.