If you run "touch /storage/.update/.nocompat" before updating (as advised on-screen) the update script will bypass the CPU architecture compat check, but I wouldn't advise doing that. Kodi is not designed for downgrades (only upgrades) so things like guisettings.xml from a newer version will be partially invalid on an older release and any binary add-ons installed will fail to run as they're compiled for arm not aarch64.
It will be better to take a backup, move it off box, clean install to the older release and then selectively restore specific things like add-on settings and thumbnails from the backup to speed up the rebuild time.