QML Tooltip width get too small after hovering multiple times

Create a simple Quick application that contains  ToolButtons and add Tooltips to them. (see attached zip file)

Run the application and then:

• Round 1: hover all the buttons (left to right) to see the tooltips .
• Round 2: Hover the buttons again (same order). Notice something?
• Round 3: Hover the buttons again. Now the tooltips width should be smaller.
• Round 4: Hover again. Smaller tooltips
• ..
• Round N: the tooltips contain a single letter per line.

Please see the attached example application and the screenshots.

The bug still appears if changeing the theme to Fusion, Universal, Material.

The tooltip text gets smaller only to 1 or 2 characters per line, then it stops shrinking.