Hi @s.schwarzfischer and welcome to the Community!
That’s odd, I’d have thought that it would allow for the consent to be set with either the Create Contact or Update Custom Entity actions.
Can you share some further screenshots showing the fields that are available in Configure section of those Create Contact and Update Custom Entity actions? We don’t have access to your Zaps so that will help to give us a bit more context on what you’re seeing in the Zap. Make sure to blur or remove all personal information (names, emails, addresses etc.) from screenshots before sharing - you can use a tool like Zappy for that.
Thanks, I look forward to hearing from you!