OK, I understand. Thank you very much
This only works if it replaces the entire property - it cannot be used to substitute just part of the value. For example, it is not possible to use CLIENT-${HOST}.
But it seems this is a limitation. In the subflow there are many mqtt subscribe nodes. For example I use Tasmota for esp8266:
stat / ROOM1 / power2
tele / ROOM1 / LWT
stat / ROOM1 / RESULT
tele / ROOM1 / STATE
Can you give me any solution to replace all ROOM1 in all topic mqtt subscribe node
