JourneySlug seems to not work

Hello can someone help me with understanding or how to properly use “JourneySlug” in payload
I am using flutter and the sample payload I am throwing is

“integration”: “Flutter - Android”,
“CUID”: “123456”,
“JourneySlug”: “comments”

now I have 2 flows
1 home and 1 comments

The Welcome start is pointing at home flow, home flow will only show a simple welcome text
the comments flow has a different text message

Is my understanding correct for payload JourneySlug the value should be the flow name? or should it be a custom event and linked to the flow? Because I also used Custom Event and no luck cannot redirect to comment on start of bot