If passwords are entered in text fields on the Oppo-Smartphone, the last character entered is shown visibly on the screen, so it is possible to read the password. If this is (not) desired, the "Show password" function can be activated or deactivated in the security settings.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Security
Step 3:  Enable or Disable  Show password
  1. Open the Settings
  2. Tap on Security
  3. Enable or Disable Show password

Oppo Instructions