After your advice and further investigation the problem was indeed the multistep form.
When switching to normal form everything is working nice.
Thank you and have a nice day.
Yes sure, I forgot,
Page is still in staging mode. Breeze off, cache deleted.
https://tychejestastie.sk/vyzvy/vlcata-sk/
Here,
I tried to embed it manually and via content editor, same thing.
