Steps to reproduce:

• Open the attached test project: it has a rectangle with animated position x/y and color
• Open Timeline view and 2D view
• Move the playhead from frame 0 to frame 100
• -> Animation should play smoothly when playhead is moved, but instead it lags
• Play the animation by clicking Play button in Timeline
• -> Same lagging and animation also stops at random frame, when it should be played from start to end and then reset to frame 0
• For some reason, animation seems to play better if animated properties are expanded for rectangle1 in Timeline view. To do so, click the arrow beside rectangle1 in Timeline view to see x,y and color properties. Then try again the playhead and play button.
• Regression to 4.7.2 and also some earlier snapshot of 4.8: not sure at wich point this broke, but at least in this snapshot it was working:
  Product: Qt Design Studio(PROJECTSTORAGE) 4.8 (4.8.0)
  Based on: Qt 6.8.2 (MSVC 2022, x86_64)
  Built on: Jun  6 2025 06:57:22
  From revision: 46a136acdf
• Tested with:
  Product: Qt Design Studio 4.8 (4.8.0)
  Based on: Qt 6.9.1 (MSVC 2022, x86_64)
  Built on: Jul 11 2025 01:25:01
  From revision: d7fde943b7