-snip-
Then a few days back I updated the app again and without changing anything, I managed to log in. I think there was a problem with the previous update, and I don't think I can ever trust that closed source wallet.
The logo has become blue and a little green above the right in the update. Now I no longer update that closed source wallet app.
Because I never open it anymore, when I open the Play Store there are two options, either Uninstall or Activate.

TrustWallet is not the wallet of choice to use for storing assets. Apart from being closed source, TrustWallet gets into trouble often enough that we can rightly call it an untrustworthy wallet for asset storage.