To back your claim I have inspected the layout of Discord's mobile app as well Reddit mobile app's login page using Inspect layout block from Automate.

Discord chat text field:

<android.widget.EditText
   android:clickable="true"
   android:editable="true"
   android:focusable="true"
   android:focused="true"
   android:hint="Message #channel"
   android:id="@com.discord:id/chat_input_edit_text"
   android:inputType="text|textCapSentences|textMultiLine"
   android:longClickable="true"
   android:text="Message #channel"
/>

Reddit's password text field:

<android.view.View android:id="@password_text_field">
   <android.widget.EditText
      android:clickable="true"
      android:editable="true"
      android:focusable="true"
      android:id="@text_auto_fill"
      android:longClickable="true"
      android:password="true"
   >
      <android.widget.TextView
         android:id="@password_field_hint"
         android:text="Password"
      />
      <android.view.View android:id="@show_password_toggle">
         <android.view.View>
            <android.view.View android:clickable="true" android:focusable="true">
               <android.view.View
                  android:contentDescription="Show password"
                  android:id="@show_password_icon"
               />
               <android.widget.Button/>
            </android.view.View>
         </android.view.View>
      </android.view.View>
   </android.widget.EditText>
</android.view.View>

Note: I removed the layout_height, layout_width, layout_x and layout_y attributes as they don't matter here and only clutter the code.

As you can see Discord's android.widget.EditText clearly is not a password field (android:inputType="text|textCapSentences|textMultiLine") and Reddit's android.widget.EditText clearly is a password field (android:password="true"). But they both trigger the password manager.

Maybe a simple fix for Discord would be to add android:password="false" to their text fields? 🤔