"Template loop detected while processing event" when calculating number of unvailable entities

Configuration
1

I am trying to calculate number of entities which have “unavailable” state:

template:
  - sensor:
      - name: strange_unavailables
        icon: mdi:null
        state_class: measurement
        state: >-
          {% set COUNT = states | rejectattr('domain','eq','update')
                                | rejectattr('entity_id','search','strange_unavailables')
                                | selectattr('state','eq','unavailable')
                                | list | count -%}
          {{ COUNT }}

Sometimes I am getting this warning:

2023-04-20 04:19:16.405 WARNING (MainThread) [homeassistant.helpers.template_entity] Template loop detected while processing event: <Event state_changed[L]: entity_id=sensor.strange_unavailables, old_state=<state sensor.strange_unavailables=59; state_class=measurement, icon=mdi:null, friendly_name=strange_unavailables @ 2023-04-20T04:17:09.645658+03:00>, new_state=<state sensor.strange_unavailables=57; state_class=measurement, icon=mdi:null, friendly_name=strange_unavailables @ 2023-04-20T04:18:09.662040+03:00>>, skipping template render for Template[{% set COUNT = states | rejectattr(‘domain’,‘eq’,‘update’)
| rejectattr(‘entity_id’,‘search’,‘strange_unavailables’)
| selectattr(‘state’,‘eq’,‘unavailable’)
| list | count -%}
{{ COUNT }}]

Looks like when calculating a value, the “sensor.strange_unavailables” is somehow involved.
Can anyone tell me how can I improve my template to avoid these warnings?

Also, may be this warning comes from enumerating “states” - regardless of presence of “rejectattr('entity_id','search','strange_unavailables')”.

Since this is a “warning” and a corr. value seems to be defined properly - surely I may not care about this warning. But I wonder is it possible to get rid of it… (do not advise me to filter it in logger)

2

Thats because “This template listens for all state changed events.”
That means every state_changed event produces render this template. Even when happen state changes of your sensor-template, there is always 'event: state_changed entity_id=‘sensor.strange_unavailable’ - that triggering the re-rendering of himself.
You need to make Trigger Based Template Sensor with another trigger, I use time pattern.
For example, this my variant:

- trigger:
    - platform: time_pattern
      seconds: "/1"
  sensor:
    - name: "Unavailable"
      unique_id: "unavailable"
      icon: 'mdi:close-thick'
      unit_of_measurement: "objects"
      state: >
        {{ states | selectattr('state','in',['unavailable'])  # include unavailable states
                  | rejectattr('entity_id','in','sensor.unavailable')  # exclude self from count
                  | rejectattr('entity_id','in', state_attr('group.unavailable_ignore','entity_id'))  #this is group with entities for exclude from count
                  | rejectattr('domain','in',['automation', 'script', 'scene', 'update']) #excluded domains
                  | list | count }}

I had the same error in my template binary_sensor, with listen for binary_sensor domain.

    - name: 'Moistures'
      unique_id: 'moistures'
      device_class: moisture
      state: |
        {{ 'on' if 'on' in states.binary_sensor 
          | selectattr('entity_id','search','_moisture\Z') 
          | map(attribute='state') 
          | list else 'off' }}

Any event state_changed for binary_sensor domain entity produce this binary_sensor-template update.
I changed domain of my template from binary_sensor to sensor:, and my warnings gone. Because event state_changed for sensor domain is not listened by that template.

P.S.: Thanks for understanding my english.