To make sure it is correct, copy this to Developer Tools → Template {{ (as_timestamp('2021-09-13 17:01:00') | int - 900) | timestamp_custom('%H:%M') }}. The result should be 16:46.
Your time sensor includes a date. However, your Template Trigger ignores the date and only uses the time. That means it will trigger at the same time every day, even if the time sensor’s value always contains 2021-09-13. Is that the way you want it to work?
If you want the automation to trigger only at the time and date shown in the time sensor, here’s a simple way to do that and it doesn’t require the use of sensor.time.
Glad to hear the suggested technique solved the issue.
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