Each year, my family decorates our Christmas tree with fairly normal red, orange, green, and blue small LED lights. However in recent years, I've been noticing that there has been a section that has failed, and they're starting to get a little flicker like a 60hz flicker. There's also just been general dimming out of a few ones (especially the blues). The lights are from 2005-2007 (there's a mix). Are they/their drivers starting to reach their EOLs?

Most sets of LED lightssets don't have a driver, its just a string of LEDs in series with some resistors.

How long they last varies allot, some sets will last for years, while others I've had sections or multiple LEDs out after not even a season's use. (usually a section out has only a single bad LED, though I've had it where every LED in the section is fried)
Thats a matter of both quality and how hard they drive them (quality varies allot and in general seems to be going down over the years!).
Normal LEDs are rated for 20ma current, but in reality you shouldn't go much more than 15ma.
When I 'make' my own sets, I shoot for 10-12ma current.
I've also actually added resistors to store-bought sets before just to drop the drive current down a bit because they were pushing it a bit too much & the bulbs just weren't lasting like they should.

With the earlier generations, for colors I found green was the most likely to fail, and blue was the 2nd most likely.

I have some indoor use color LED string that has a total power of 1,35w. It is either from 2020 or from 2015 and it has been in use as just some fun lighting accent every evening since that year. No LED or driver failure, only the cable has some mechanical damage from being a somewhat firm type of PVC isolation, making it prone to cracking.

Wow these are about on their 20th season! I forgot that these just have a resistor lol

@xmaslightguy I've noticed the greens and the blues go out first too! Though the first failure which was a one off thing was around 2015-6 with a orange/yellow one. The blues and greens on our sets dim out mostly. But I have seen two that flicker randomly a bit. One was near an electronic RS ballast and it acted up more then the light was on, so I wonder if there was some sort of interference.