you can only distribute your source under the licence of the source code, yes. just like copyleft licences. The whole concept of open source is demonstrably, flaky.
You want it to be a concept closer to free software, I say if the source is open, you can modify it and your changes are able to have an effect then it’s open source.
I don’t think we are going to resolve this. I would prefer if it was free software but that’s not gonna happen for godot or unreal engine