Steps to reproduce:

1. Create and open a new project
2. Create a new Terrain Brush asset (just for demonstration) and select it
3. In the Inspector, open the Object Picker window for Mask Texture
4. Unhide "Hidden Package Assets"
5. Hold the down arrow until the bottom of the list is reached, then close the Object Picker
6. Observe the Task Manager

Actual results: More memory is being used than before step 5

Expected results: Memory is relieved upon closing the Object Picker

Reproducible with versions: 2023.1.0a10, 6000.0.73f1, 6000.3.14f1, 6000.4.6f1, 6000.5.0b6, 6000.6.0a4

Tested on (OS): Windows 11 Pro (25H2)

Notes:

• Can be reproduced again and again, by doing steps 3-5
• Reproducible with any object reference field in the Editor
• This is likely related to the previews generated for each selected asset in the Object Picker window