What kind of things can GTM do?
a) It could prevent normal operation of a system by making unexpected changes (Availability)
b) Depending on how you have it set up, it could potentially change your response data or omit some of it (Integrity)
c) It can also read all the content on the page, as that is what it is designed to do - this may be in breach of local data protection regulations (Confidentiality)
As this is a third-party tool, we have no control over what it does when it is embedded into our applications. Depending on its configuration (this is set up by you, the GTM account holders) it may do one or all of the above and we are powerless to know what it is doing, therefore we are unable to support Google Tag Manager.
For all of these reasons we'd ask you to think very carefully indeed before opening up your website to this kind of risk. If you do still wish us to embed Google Tag Manager code for you then this is at your own risk and will invalidate your SLA with us should Google Tag Manager be the cause of any disruption or loss of service/data.
If you wish to collect analytics data, the use of other tools like standard Google Analytics tracking will perform this task. While we do not recommend you use any of these tools without proper thought and care, you can find out more information about Google Analytics on the Google website or in these articles we've written to help you: