In Netherlands production the google tag manager script (Google Tag Manager Identifier planet4 setting) sometimes is included in the page response and sometimes not.
I suspect that it has to do with the 'Enforce Cookies policy' planet4 setting being enabled.

If 'Enforce Cookies policy' planet4 setting is enabled, the user has to consent to cookies in order for the gtm script to be included.
I think the problem is that the cookie's value (cookie: greenpeace=2) does not make it to the application and the app serves the cached content.

Investigate why it is happening and if possible change the way that gtm script is included in page.