The issue is caused by an update to Android System WebView. You can either:

  1. Revert to the stock version of WebView/Chrome from the Play Store and disable the updates of the app.

  2. Use a workaround by disabling Aqua Mail's New Message Editor in Settings > Composing and Sending > New Message editor.

    Android System WebView is a system component maintained by Google which handles various functions inside apps. On some devices and Android versions, instead of WebView, Google Chrome is used for the same functions. We also have an extensive discussion on our forum