This is a known issue. Ad blockers and privacy-focused browsers block scripts like Google Analytics and Google Tag Manager by using filter lists based on domains, JavaScript patterns, and URL paths (e.g. googletagmanager.com, /collect, etc.).

One solution recommended across the internet is server-side GTM (ssGTM), which claims to reduce the impact on analytics and marketing tools from ad blocker. But nowadays even first-party ssGTM setups get blocked by URL patterns, and if not ssGTM itself (for instance, if it uses some custom load script), then other products used by GTM are blocked. I even wrote an article explaining why server-side GTM isn’t a complete solution against ad blockers.

A more robust approach would be the network-level protection.

To prevent GA or GTM from being blocked you can route requests through a protected proxy channel that masks both the destination and the structure of the calls. This approach remains fully compliant – as long as you aggregate data properly and ensure user consent.

DataUnlocker solves this by handling technical blocking at the network level. It reroutes tracking requests through a customizable endpoint that avoids detection by ad blockers, and moreover ensure this channel can't be affected and compromised, long-term.

Disclaimer: I’m the founder of DataUnlocker. I’m adding this here because this thread still shows up in search results and I hope this explanation helps others facing similar issues.

DataUnlocker can be integrated into any web app and complement all existing marketing products you have there. A few steps to install it and your tools are protected:

1. Set up a transport endpoint on your domain — a proxy for network requests.
2. Integrate DataUnlocker into your frontend, either by attaching it to an existing script or using its native integrations.
3. Enable Network Protection, by selecting which outbound tracking requests (e.g. GA, GTM, Meta Pixel) to protect via the proxy.

Result (with ad blocker enabled):