GIMP 3.0 has been more than one decade in the making as the port from GTK2 to GTK3, also transitioning away from Python 2 to Python 3 support, and a wealth of other improvements from the UI to lower down into enhancing this open-source Photoshop alternative.
The GIMP project announced on X/Twitter today that they have entered the string freeze for this much anticipated release.
That is probably where they got it, but the word definitely had multiple uses at the time. It may not have been explicitly ableist, but it is and was an ableist word. It also invalidates their claim that they are trying to reclaim usage. Again, they named it that because they thought it was funny, not some grand scheme.