As i said: This folder is the cache of the shop. The timestamp at the end differs because it is the revision of the currently running version of Shopware. This version changed after your update, so does the name of the folder.
The maintenance page get’s displayed because the shop is still in update mode. It determines that it is in this mode, because there is a folder called “update-assets” in the root of the shop folder. Please rename this folder and check if the shop runs then.