It wasn't me https://github.com/osmandapp/Osmand/issues/6078
:D
Answer found:
Go to My Places / Tracks, tap on the track. Then tap on the pencil icon, this will enter edit mode. Zoom to the location you want to edit. If you zoom in close enough you will see blue circles. Tap on the blue circle where you want to trim/split the track. A menu will open allowing you to trim and split the track. Here you can also move track points or add additional points.