Welcome back!
Well, a few things has changed, to start with:
-No more trade system, whatever you lost/lend/borrow/sold, will probably not come back
-Max lv is 125
-There are BB7 and CV7 which are highly cost in real money
-New event/premium BBs/Cvs/SSs
-Now its super easy to grind up
-Depending on your timezone, for America, the afternoon are quite slow, there is always 1 Great Battle or 2 set up, running with players, Asia-Chinese players "fill" the game on nights.
-The playerbase is mainly Chinese players
-Due to Covid19, a lot of old players returned such as  myself.
- As a personal opinion, download the game through Steam, better stability
-New Chinese Nation: there is only 1 CV, a few DDs and CLs, completely unbalanced regarding support slots, torpedos among other things.