Liquid Markup Filters & webhook notifications

I've only dipped my toes in Liquid Markup a few times - so this may be a bit of a newb question.

Problem Statement: We are facing a challenging scenario with our JIRA integration - when we merge a ticket in Zendesk that has an open incident in JIRA, we want to send a notification to JIRA via webhook with the new Zendesk ticket id. 

We've built a trigger that fires on the comment text “This request was closed and merged into request”

The action is simply a notify by > active webook with the following body:

{
 "this_ticket" : {{ticket.id}},
 "merged_into_ticket" : "{{ {{ticket_latest_comment.value}} | remove: 'This request was closed and merged into request #' }}",
 "JIRA ID" : "JIRA ID"
}

(Note: I get that this only partially does what I need it to do, but taking babysteps here)

When I review the webhook activity I see the following:

{
 "this_ticket" : 48892,
 "merged_into_ticket" : " | remove: 'This request was closed and merged into request #' }}",
 "JIRA ID" : "JIRA ID"
}

I also set up an email notification that's has a simple body:

{{ {{ticket_latest_comment.value}} | remove: 'This request was closed and merged into request #' }}

I see the same when on the email notification I receive, though:

I'm kind of hoping I'm missing something simple (admittedly, I am having one of those days) - but wondering if there are some Liquid filters that don't work in Zendesk?

Any insight / guidance / magic from the community would be greatly appreciated.