Just finished replaying the update scenario from your version to the latest on in a VM - due to the age of your installation (3.3.14 is rather old), there are some steps involved in getting up to date:
3.3.14: Run sudo ostree admin upgrade, this will lead you to version:
3.3.20: Run eos-updater-ctl update, this will lead you to version:
3.9.4: This is the current version. Now, when at this version, update all applications:
flatpak update --appstream -y
flatpak update -y