Regression[5.14.2->5.15.0] Popup Positioning with scale is broken

Popup Positioning with scale is broken, please find the attached sample
The animation provided serves to create the following impression:
1) show only the title of the dialog, and scale width and height out from its center to reveal the full title, centered in the parent
2) gradually reveal the content and the footer using a vertical animation (without scale) by manipulating the implicitHeight while clipping is turned on.
The animation speed can be slowed down using a common duration property.
It works fine in 5.14.2 but initially positions way off center in 5.15.0 and pops back to the center only after the scale animation sets the scale to 1 (and before the transition has completed).

It seems to be the regression of QTBUG-73687