This means you have a Pro feature on your mobile site. Unfortunately, I do not know which element this is. Most features are included in the free account, but not all.
My best suggestion would be to rebuilder your website in our newer builder, WebsiteBuilder. This newer program is more updated and modern, but it also has a mobile editor built into it so you don't have to use a 3rd party company like DudaMobile, who doesn't have great support and it difficult to work with. It would not cost anything additional for you to create this new site and your old site can stay active while you build it. If you have any questions about this, I'll be happy to answer them