I think that's not normal. I think you can send a support ticket.
Don't be mad, the problem is for sure under intention. Just read this topic, where it's all about the problem that you pointed
out perfectly.
https://forum.beta.forgeofempires.com/index.php?threads/gbs-and-eras-dislike-and-suggestion.7827/
I'm aware of ballance problems in the game, caused by GB's and I think Inno too. Since they decided to not release
the second OF GB's because of the impact of GB's on the game in general. It might be already too late to stop it,
like the PvP ballance 90% attack vs 60% and almost limetless defensive boost from watchfires. The Arc just did make
a problem with massive GB's bigger, by making it eassier to achieve high GB lvl's.
So far I know the major ballance problems with GB's started after the cap of lvl 10 was gone. Before it was just the
PvP ballance that was gone by introducing watchfires and the GB's. Later on when GB's where able to grow endless
strong, in the current days, mayor problems with ballance come with OP high lvl GB's. Inno attempted to prevent it
with small steps with the bonusses above lvl 10, but time learned that it's not enough, as you pointed out. For example
Alcatraz was OP in eurly development on Béta, but was nerfed to what it is today and that was good, but with endless
levels, it's possible that Alcatrazz gain the same OP stats and far beyond.
A cap on the highest possible powerfull bonusses are maybe the sollution. When you acieved that point, no mater how
high the lvl of your GB will become, it will not be able to acieve stronger stats, just points and points don't fight nor boost.
Simelar with lvl 10 cap. For Alcatrazz it would probaly a cap on X units/day, but endless more happines would not hurt,
right? Do you think that's a sollution in the long run? or do you have a much better sollution?
About the events, I'm not sure how event buildigs can bring new players in disadvantage. Perhaps they where buyed
with lots of diamonds, during Summer Event.
By the way, I don't mean anything offensive.
So pleas don't be anger on me, I try to understand you
and to think with you to a sollution to improve the game. So Inno might be able to work on the
problem with our feedback.