We just published Shopware v6.5.1.1 as a Patch Release with the following bug fixes:
Webpack config deleting the whole Resources/public directory of plugins when building the administration
Shopware Installer updating always to the latest version regardless of the chosen version
Thank you for your support 
Wieder wurde es im Admin (6.5.1.0) nicht angeboten.
Hat sich da seit 6.5.0 etwas geändert?
via console war es kein Problem.
Thanks for reporting, @sonic. This issue was already reported and fixed for upcoming updates. (I reckon the ticket will be updated soonish.) In the mean time, it is possible to use update via terminal once as described or to delete (resp. re-name) config/packages/shopware.yaml in order to see updates in admin panel again.
BTW: it is highly appreciated to respond in the language of the thread opening. Otherwise it is going to become max confusing for everybody not speaking German. Thanks for that 
If your current version is 6.5.0.0 you have to rename/delete that file or change the value for the update from false to true. Then clear the cache. Without that change, no further update will be shown in the admin backend.