MWB For all the things that we can accuse pixel federation of, getting the news out about changes in the game, usually isn't one of them.
✉ There is an envelope icon on the right side of your playing screen. Pixel federation sends us players information multiple times a week, and especially about the changes with each update on Tuesdays. Make yourself a more informed player by checking out the News icon....
... Especially on Tuesdays.
It appears that you have been playing a long time, and should have been aware that periodicily pixel federation adds a new townhall level during a Tusday update.