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.