amp-pixel is lost in AMP Cache

Question

Why is an amp-pixel tag like this lost in the AMP cache?

<amp-pixel src="https://amp.abendzeitung-muenchen.de/_CPiX/art-706352-60/706352.gif?RANDOM" layout="nodisplay" class="i-amphtml-element i-amphtml-layout-nodisplay i-amphtml-built" i-amphtml-layout="nodisplay" aria-hidden="true" hidden=""></amp-pixel>

Here the link to the original website (you can find the amp-pixel tag) https://amp.abendzeitung-muenchen.de/muenchen/vorlaeufiger-corona-kassensturz-fast-tausend-euro-pro-kopf-verschuldung-in-muenchen-art-706352

and the link to the same site from the AMP Cache (the amp-pixel tag is gone) https://amp-abendzeitung--muenchen-de.cdn.ampproject.org/c/s/amp.abendzeitung-muenchen.de/muenchen/vorlaeufiger-corona-kassensturz-fast-tausend-euro-pro-kopf-verschuldung-in-muenchen-art-706352

Answer 1

The cache serves a stale version of your page. If you cache-bust the URL, eg: https://amp-abendzeitung--muenchen-de.cdn.ampproject.org/c/s/amp.abendzeitung-muenchen.de/muenchen/vorlaeufiger-corona-kassensturz-fast-tausend-euro-pro-kopf-verschuldung-in-muenchen-art-706352?asdfasdfsa you'll get the amp-pixel.

I'd recommend serving AMP pages with a lower max-age to make sure changes get propagated quickly.