How to reproduce:
1. Open the attached “IN-14037” project
2. Open the “bug” Visual Tree Asset file in the UI Builder
3. Switch the ScrollView theme from current to “Unity Default Runtime” and back

Expected result: Low and high buttons theme of Scroller are updated to the corresponding ScrollView theme
Actual result: Low and high buttons of Scroller theme remain as for “Unity Default Runtime”

Reproducible with: 2021.3.8f1, 2022.1.14f1, 2022.2.0b6, 2023.1.0a8
Couldn’t test with: 2020.3.38f1 (runtime UI not supported)

Reproduced on: macOS 12.3 (Intel)

Note: Themes are set correspondingly for all objects after re-opening the UI Builder

Before doing anything, with Active Editor Theme (Dark):

!screenshot-1.png|thumbnail!

After switching to Unity Default Runtime Theme:

!screenshot-2.png|thumbnail!

After switching back to Active Editor Theme (Dark), notice up and down arrows that have different looks and thumbnail is also wrongly styled:

!screenshot-3.png|thumbnail!

Note: to work around this, Reload the Window or reopen UI Builder