I had front and rear LED lights on my A4. Rear ones failed just inside the 3 yr warranty - one LED out on each side. They had to replace the whole light unit each time.
Up until that point, I'd have agreed that LEDs were more reliable. Now, not so sure they're a good idea on car lights unless you can user-replace one LED at a time.
We use some cluster LED lights at work, & when they start to fail, you can see them one by one dimming until finally they drop out completely.
My partner has an Evoque, less than 8 months old & it has a couple of the brake LED's out.
Never been bumped or knocked.
Most likely a dry solder joint, but my issue is as previously mentioned, its not just a single LED needs replacing, its the complete & very expensive light unit!