They did start a cloud service for hosting Gitea which introduces a direct incentive for them to make Gitea less hosting friendly by, for example, making newly added configuration options less comfortable to set up. And more recently some changes to code contributions that are not exactly community friendly (as a result forgejo will be unable to upstream some of their changes)

What lead to Forgejo, as far as I am aware, was less a problem that is already there and more the set of problems that have a very high chance of eventually manifesting, at which point forking the project would be too late.