Thanks for the hint Simon! Indeed canonical seems to be what I was thinking about. I tried it but it does not complete work, it embeds a canonical URL which points to itself, not to the RSS source:
<link rel="canonical" href="https://community.domain.com/t/invoicing-mandate/537?page=0" />
instead of
<link rel="canonical" href="https://blog.domain.com/t/invoicing-mandate/537" />
(This is stable/3.2.0)
Also, can/should this be set as featured link as well?
In our case we dont use truncate (however the RSS Feed is already truncated). But I hope Google will accept it anyway.