There’s 2 different image implementations. One is ours, the other one (image icon at the far right of the toolbar) is called Uploadcare, which is what you’re seeing.
If you don’t want to use uploadcare, you can disable it through the redactor.plugin_uploadcare system setting.
The other image button (halfway in the toolbar) will follow your configured upload path.
In the next release we’re disabling the uploadcare plugin by default. It’s a bit of an advanced feature that also needs configuration before working correctly (needs an API Key), so it makes sense to make it opt-in, rather than opt-out.