MQTT, messages from offline devices

I really hope not.

But in the mean time I was populating the flow with debug nodes.

This is not looking good.
Order of the debug nodes:
RAW IFF
After JSON
Reformatted1
Reformatted2

RAW IFF 11:22:49 TimePi
RAW IFF 11:22:49 BedPi

After JSON 11:22:50 TimePi
After JSON 11:11:50 BedPi

RAW IFF 11:22:50 TelePi

After JSON 11:22:50 TelePi sent 11:22:49

To here it looks good.
3 devices sent their replies. All different messages out of the JSON node.

Reformatted1 11:22:50 TelePi sent 11:22:49
Reformatted1 11:22:50 TelePi sent 11:22:49

Reformatted2 11:22:50 TelePi sent 11:22:49
Reformatted2 11:22:50 TelePi sent 11:22:49

This is a worry. Suddenly I have TWO TelePi messages of which one didn't exist a second ago.

Reformatted1 11:22:50 TelePi sent 11:22:49

Reformatted2 11:22:50 TelePi sent 11:22:49

RAW IFF 11:22:53 GPS

After JSON 11:22:53 GPS

Reformatted1 11:22:53 GPS

Reformatted2 11:22:53 GPS

On the GUI side of things I have/see this:

Screenshot from 2022-03-04 11-39-50

This is the actual flow.
So there isn't really anywhere the messages can be corrupted.