The prevalence of chromium forks makes me wonder if there is something about the Firefox code base that makes it far less attractive to work with then chromium’

The prevalence of chromium forks makes me wonder if there is something about the Firefox code base that makes it far less attractive to work with then chromium’s. Is it just raw features of the core engine? Or is there a bigger issue? I believe the chromium team does put some effort in helping even competing forks with technical issues. I wonder Mozilla is unable to demonstrably provide support in this area?