My set of lights from June 2021 finally had a cluster of LEDs stop working. For the fun of it, I pulled it apart. It doesn't look like any water got inside, but I did find a single dead LED in a cluster of 3.
I ordered up a new set and can report that current units still look and blink identically. The only difference I noticed is that the electronic module now come pre-sealed with some sort of glue around the shrink tubing. This means you can't easily re-solder the wires, and you will need to use some sort of external splice.
Since the LEDs look the same, I didn't bother replacing both of my sides. I figure I'll keep using my other side as long as it lasts, and wait to replace it until it actually has a problem.
I figure I'll just treat these as a consumable, and replace them every few years when they burn out.