Reproduction steps:
1. Open the user's project
2. Open UI Builder (Window > UI Toolkit > UI Builder)

Expected result: no errors
Actual result: 2 errors:
1st error - Unexpected recursive transfer of scripted class. 'BuilderDocument' is being transferred while trying to transfer 'LiberationSans SDF'
2nd error - UnityException: get_shader can only be called from the main thread.
Constructors and field initializers will be executed from the loading thread when loading a scene.
Don't use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function.

Reproducible with: 1.0.0-preview.15 (2021.2.0b15), 1.0.0-preview.16 (2021.2.0b16), 1.0.0-preview.17 (2021.2.0f1), Built-in (2021.2.13f1), Built-in (2022.1.0b9), Built-in (2022.2.0a4)
Couldn't test with: 1.0.0-preview.18 (2019.4.36f1), 1.0.0-preview.18 (2020.3.30f1), 1.0.0-preview.10 (2021.2.0b1), 1.0.0-preview.14 (2021.2.0b10), 1.0.0-preview.18 (2022.1.0a15) (package errors when converting the project)

Note: for 2022.2.0a4 2nd error starts with "GetName" instead of "get_shader"