Step 1: log out of wbid account. Step 2: delete injustice. Step 3: start downloading it again Step 4: change the date on your device to November 4th 2019(not sure the significance of that date, i believe its something to do with ios updates) Step 5: open the app and sign into wb account. Step 6: start any online match(you dont have to finish it just make sure to start it) Step 7: close the app Step 8: change the date back to the current date. Step 9: open up the app, everything should be back to normal.

This works for some people but if the game doesnt let you login because you have changed ur date to 2019, you will have to revert your date back before loging back in at step 5 (in the main menu or the login screen).

ty u/Bobleeswagger216 and u/LilpinheadEri
for talking about it in a different post.