Yes, really.
Security patch level … https://gitlab.e.foundation/e/os/releases/-/releases/v3.1.1-t
Android version upgrade …
It’s the circle arrow top right next to the three dot menu.
You can wait. As you can see in the weekly development update I referenced above, the OTA upgrade from Android 13 to 15 on FP5 is currently planned for /e/OS version 3.3.
A 3.1.4-t-official update staying on Android 13 is available on the OTA server, so your updater should see it.
You could try to tap the refresh button in the updater several times to perhaps make the update available on your phone, or you could try to clear cache and storage of the updater App and try again.
Settings - Apps - See all … apps - (3 dot menu) - Show system - Updater