Petro, this is a working variant:
trigger_variables:
INPUT_WAIT_PERIOD_BEFORE_UPDATE: !input input_INPUT_WAIT_PERIOD_BEFORE_UPDATE
trigger:
...
for:
minutes: "{{ states(INPUT_WAIT_PERIOD_BEFORE_UPDATE) | int }}"
I found out why I considered this code as non-working - I just switched off notifications via Telegram earlier: no notifications → doesn’t work. Such a stupidity)))
Thank you VERY MUCH for helping!