REST Syntax for user disable LTM Node

That seems like a bug. HTTP::path should only return or set the path in the URI without retrieving or modifying the query string. You could work around this using HTTP::uri instead:

 
 when HTTP_REQUEST { 
  
     Check if path is / 
    if {[HTTP::path] eq "/"}{ 
  
        Parse the URI into the path and query 
       scan [HTTP::uri] {%[^?]?%s} path query 
  
        Check if there was a query 
       if {[info exists query]}{ 
  
           Update path, preserving query 
  HTTP::uri "/en-CA/default.htm?$query" 
  
       } else { 
  
           Update path without query 
  HTTP::uri "/en-CA/default.htm" 
       } 
    } 
 } 
 

I'd also suggest opening a case with F5 Support on the possible bug with HTTP::path removing the query string. Which LTM version are you running?

Aaron