Another alternative to reducing unclaimed energy sources capacity (first two changes in the changelog) would be limiting the reservations count available to a player depending on his/her GCL. Say, three reserved rooms per one claimed room.

I like this idea much better. Having no limit on room reservations essentially means there is no cap on how much energy you can bring in(EDIT: other then spawn ticks), and simply adding a limit would be a better solution rather then nerfing everyone. My only suggestion, rather then basing it on GCL, it may be better to base it on actual claimed room number (ie GCL 7 player with 3 claimed rooms, would have 9 reserves not 21).  This should make people spend more energy on defending their rooms too, as the number of claimed rooms with dictate how many remote mines you can have.

This has been a problem with some SK rooms for at least a month. My previous base was next to W44N14 and I know it was broken back then as I was able to mine it no problem. There were no source keeper lairs in the room at all initially, and then maybe a week later they suddenly showed up but did not do anything. You can actually see that there were no lairs initially in these rooms by looking at the world map picture back from July. The only pattern I have noticed is that all of the broken rooms are in the bottom right section of their respective sectors.

World Map from July: http://support.screeps.com/hc/en-us/articles/209471709-Screeps-World-Review-July-2016