Easy Installer should install an official build /e/OS official redfin download – this is currently Android 13 (T). As a general rule one would not use /e/OS to downgrade Android version.
@Dam
The GrapheneOS factory images flash an Android Verified Boot Key that must be deleted to fully reset the device. Then delete the custom Android Verified boot key so as not to trust it:
fastboot erase avb_custom_key
Noitz: This is only necessary if the /e/OS web installer does not do this.
If going from GrapheneOS I would first go back stock ROM Android 14 using the most current stock ROM for that device. Use the Android flash tool for that found here: https://flash.android.com/welcome
In the command line instructions it says eOS t is official (Android 13), and eOS u community (Android 14) are available. In those instruction it say to be at Android 14 (hopefully it applies to the official eOSt build).
Either way if it doesn’t work out with the easy installer just use the Android flash tool to go back to stock ROM.
I have always gotten best results with the command line tool. Maybe someone else can clarify it eOS t needs to be at android 14 or android 13.