AMP Email Template Insider Issue - MAPCLUB

### Description

MAPCLUB had already requested AMP, and the request was approved successfully. After that, we conducted several rounds of testing to ensure everything was working as expected. At the beginning, the tests were running smoothly and we were able to see the AMP emails displayed correctly.

However, in the middle of our testing process, the functionality suddenly stopped working. The AMP content could no longer be displayed properly, and in the test email we received an error notification stating: “error displaying dynamic content (invalid_amp).”

This means that although the setup was initially working, something caused the AMP to fail during subsequent attempts. We’re currently reviewing what might be causing the inconsistency so we can identify whether it’s a technical issue in the AMP setup, validation, or rendering process.

### Reproduction Steps

Please Refer to this ticket for reference
https://github.com/ampproject/amphtml/issues/40394#issuecomment-3375842533

### Relevant Logs

```shell

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### Browser(s) Affected

Chrome

### OS(s) Affected

_No response_

### Device(s) Affected

All Devices

### AMP Version Affected

_No response_

Start with the referenced ampproject/amphtml issue 40394 and its linked comment, then reproduce the AMP email in Chrome using the reported testing setup. Investigate the “invalid_amp” error and determine whether the failure is in AMP setup, validation, or rendering; done means the AMP content displays correctly again.

Written by the indexing model from the issue text.