Steps to reproduce:

1. Create Script item type with some parameter having value e.g. {$TEST_MACRO} and code e.g.:

   var script_params = JSON.parse(value);
   return JSON.stringify(script_params);
   

2. Fill user macro {$TEST_MACRO} with doublequoted value, e.g. "SUBMITTED", or "SUBMITTED","REPEATED", and so on.
3. Initiate item execution and see it in latest data.

Result:

Cannot execute script: SyntaxError: invalid json (at offset 17)
at [anon] (duktape.c:34562) internal
at parse () native strict preventsyield
at [anon] (function:1) preventsyield

Expected:
The same as when doublequoted value in script parameter directly (not via user macro), but directly it is working without error, e.g.:

I haven't found in documentation https://www.zabbix.com/documentation/current/manual/config/items/itemtypes/script that these two cases should have different parameter parsing / escaping ...