Thermostat card showing wrong units

my HA is configured for Metric units:

I configured a generic thermostat using a Fahrenheit sensor

- sensor:

    - unique_id: sensor.devboard3_ds18b20_2_temperature_f
      unit_of_measurement: "°F"
      device_class: "temperature"
      state_class: "measurement"
      state: "{{ 1.8 * (states('sensor.devboard3_ds18b20_2_temperature') | float) + 32 }}"

- platform: generic_thermostat
  name: Thermostat ex pool heat pump
  unique_id: thermostat_ex_pool_heat_pump
  heater: switch.devboard4
  target_sensor: sensor.devboard3_ds18b20_2_temperature_f
  min_temp: 30
  max_temp: 100
  target_temp: 75
  min_cycle_duration:
    minutes: 30
  away_temp: 50
  precision: 0.5

All good so far. Thermostat works as expected.

however, when I try to add the thermostat card the values are correct but the units shown are Celcius… Not a conversion issue, just the wrong unit displayed.

I’ve tried changing to unit_of_measurement: “F” (without the degree symbol to force “F”) but still no success.

what am I missing?