If your lights flicker it usually means you have a poor connection somewhere. remember it takes very little voltage to turn on a LED lamp ( .7volts for a single LED element) so any slight imperfection and you get issues.
If you can get some antioxidant spray and apply it to ALL connections and then tighten the connections, you have a better chance.
If you have replaced your old incandescent lamps with new energy efficient LED lamps this is a classic case of what can happen.
Never change external lamps (markers lights, brake lamps or headlamps etc) with LEDs in old incandescent fixtures without applying antioxidant spray, if possible replace the entire fixture for a LED one.
This also applies to grounds connections too not just positive wires.
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