They called Defold "open source" at the beginning and only changed the wording later when people started reacting, so this could be an artifact left from that.

The main repository (github.com/defold/defold) is the only one with the Defold License (ie the modified Apache license). There's also around 80 or so MIT licensed repositories with Defold engine plugins for things such as analytics, monetization, ads, attribution, game servers as well as tools such as Spine, Tiled, Rive etc.