Hey @daniello,
I checked the workflow that you shared here: 0.134.0 Mqtt Trigger broken - #6 by daniello
I tested it and I got the following result
If you observe, the value in the message that I get is a string. To get the boolean, you should enable the JSON Parse Body additional option. This will return the values with the right data type. You can then refer to the value in the IF node.
Here’s the output with the JSON Parse Body option.
Here’s the updated workflow