Blender makes videos in Safari fast forward

Strange behaviour in Safari (MacOS 10.14).
When Blender is active, videos in Safari (i.e. Youtube) fast forward to the end (not always). When quitting Blender, it’s normal. (tested in 2.81, 2.82, 2.82a)
Can someone else confirm this?
Blender bug? MacOS bug? Safari bug? My machine bug?