I tried PHP 7.1, 7.2 and 7.3 but the code was displayed raw. When I went back to 7.0 it worked as it should. Problem is that I have to pay huge amounts for extended support of 7.0.
I know that the developer of SyntaxHighlighter Evolved tragically died of cancer but perhaps somebody can help with a workaround?
In case that this may help, here is the link to my blog: http://blog.ephorie.de
Full disclosure: I posted this question in the official support forum weeks ago but got no reaction: https://wordpress.org/support/topic/php-version-7-0-dont-work/
Hopefully somebody here can help... Thank you!
The issue was resolved with version 3.5.5.