How to reproduce:
1. Open the attached user project “UIToolkitEscapeSequenceParsing.zip“
2. Open Scene “SampleScene“ (Assets/Scenes)
3. Enter Play Mode

Expected result: Text is displayed correctly
Actual result: Square symbols appear in the text

Reproducible with: 2021.3.18f1, 2022.2.0a8 
Not reproducible with: 2022.2.0a9, 2022.2.6f1, 2023.1.0b3, 2023.2.0a2
Can’t test with: 2020.3.45f1 (Errors in the Console)

Reproduced on: macOS 13.0.1 (Intel)

Note:
- Issue is reproducible in Builds (although instead of a square symbol, nothing is shown)
- If at least three characters follow a "\u" and they do not form a valid unicode escape sequence then the entire sequence will be replaced with the "square" unicode character
- If at least seven characters follow a "\U" and they do not form a valid unicode escape sequence then the entire sequence will be replaced with the "square" unicode character