glide.installation.production

can be set to "false" in sub-prod instances > should not be changed! See why here

https://support.servicenow.com/kb?id=kb%5Farticle%5Fview&sysparm%5Farticle=KB0818410

try this approach instead:

instURL = gs*.getProperty('glide.servlet.uri');*

if (instURL*.indexOf('https://xxxprod.service-now.com')* > -1*)* {

gs*.print('Not to be run on prod!!');*

}