This happens due to this code in qxcbconnection_xi2.cpp:
// If we have found the valuators which we expect a tablet to have, assume it's a tablet.
The point is, the touch part of this device also has pressure, proximity and absolute axes.
The valuators have the following limits:
The output of xinput:
|For Gerrit Dashboard: QTBUG-39572|
|87238,5||xcb: distinguish Wacom touch devices from tablets||dev||qt/qtbase||Status: ABANDONED||-2||0|
|87378,12||xcb: support Wacom touch devices; distinguish from tablets||5.3||qt/qtbase||Status: ABANDONED||0||0|
|92523,4||xcb: support Wacom touch devices; distinguish from tablets||5.4||qt/qtbase||Status: MERGED||+2||0|