/amp/ does not work anymore-critical issue, still not resolved

Hi,

I updated to Version 0.9.38 with no changes in configuration of the AMP-plugin. Mobile redirection switch was and still is off. Previously the request of a /amp/ subpage worked fine. No all /amp/ subpages are redirected to the non-amp version, although AMP is activated in the page settings. we didn’t change any rewrite rules.
Strangely only the /amp/ for the homepage/startpage is still working. All other don’t work anymore. Instead suddenly we can force amp-output only by adding ?amp to any URL. But that is not good as it conflicts with canonical Tag.
– we deleted the cache: no change in behaviour
– we re-saved the wordpress permalink settings: no change
– I even de- and reinstalled the AMP-plugin itself: no change

Try for example to request this URL (on desktop or mobile, doesn’t matter):
https://www.sunny-one.de/de/website-launches-und-relaunches/amp/
Since the update of your plugin it is redirected to the non-amp-version:
https://www.sunny-one.de/de/website-launches-und-relaunches/

WHY? How can I fix this? I don’t want to introduce redirects from /amp/ to ?amp to work around this issue. Is anyone aware of this problem here?

Can anyone please send me a link to the PREVIOUS version of this plugin or is a rollback not possible?

I get a lot of crawling errors for /amp/ now in google search console, very bad.

Regards,
Robert