The code is shown in one line.

[apys]

Enlighter 4.6.1
Twenty Fifteen Theme
TinyMCE Editor
Iubenda plugin 3.5.9 *
and others

Iubenda plugin interferes with code presentation,

[AndiDittrich]

hi @apys ,

you've already identified the "weak" thrid party plugin - just disable it or contact the related plugin authors for support.
this is not an Enlighter issue