I experienced this. Here’s my story…
Changed my reverse bulbs to Sylvania LED’s awhile back. Nice and bright. No issues.
Then I came across these
Anzo Sequential LED Taillights at Vivid Racing. They are badass; trust me. Installed them on the truck. All was good… for about a month. The driver side started to fog/ get condensation inside.
Anzo sent me another set. On that set the passenger side LED failed to illuminate just after the first 30 days.
Sent them back for a full refund. Found them cheaper at Parts Geek of all places. Since I’m a gluten for punishment I got them. Driver side fogged again. But, this time I noticed something. The gasket on the afternoon LED reverse bulb was thicker than the OEM setup; made it much harder to install. What I noticed was it was so hard to install that it had become deformed under the pressure.
When I got the bulbs installed I added a little dab of rtv around the base of the bulb where it meets the taillight house.
That fixed the issue. Been since September-October when this was accomplished.