This is expected GNOME behavior, not a Framework bug: the top-bar icon shows the battery state reported by UPower, not the AC adapter status. When the battery is full, the embedded controller reports Full (or Not charging), so GNOME shows the plain full battery instead of the charging bolt — even though the charger is connected and powering the machine (Ask Ubuntu, Ask Ubuntu).

You can confirm it yourself:

cat /sys/class/power_supply/AC0/online   # 1 = charger connected
cat /sys/class/power_supply/BAT1/status  # Full / Not charging when full

GNOME Shell has no built-in setting to change this, but you have options:

1. Install a GNOME extension that indicates AC status. The most cited is Battery Health Charging, which has a "Change battery indicator icon behavior" option — when enabled, the icon shows the charger/plug status rather than the charge state, so it keeps indicating "plugged in" at 100% (Ask Ubuntu). Note: on Debian 13 (GNOME 48/49) check that the extension supports your shell version before installing.

2. Use a status/monitoring extension like Vitals or a configurable battery icon extension that reads AC0/online directly.

3. Alternative workaround: set a Framework charge threshold so the battery rarely sits at 100% — e.g. echo 80 | sudo tee /sys/class/power_supply/BAT1/charge_control_end_threshold. Below the threshold the state stays Charging-like, though at the threshold it will again show Not charging/full, so this only partially helps.

The simplest reliable fix is option 1: an extension that keys the icon off the charger instead of the battery.