Hey @rizaardiyanto, thanks for the link! I was searching for other topics regarding the same problem before opening this one, but couldn’t find one. Problaby due to the fact that “by” is a very common word ??.
I tried it on my page and it works, although it’s not the perfect solution. Deactivating the author information for the single post template removes the “by” but also the author’s name at the start of the post. I found a workaround with the hook “generate_post_date_output”. I use a mix of PHP (for the publish-date) and PP-Authors Shortcodes to include the meta-info I want. Just if anybody else is facing this problem :).