Reproduction steps:
1. Open the attached project
2. Open "Assets/Naming test" Shader Graph
3. Create new Property and name it “name _something”, underscore after space is important
4. Select created Property and inspect the Reference field

Expected result: Reference field doesn’t have two sequential underscores in its name
Actual result: Reference field has two sequential underscores in its name

Reproducible with: 12.1.7 (2021.3.7f1), 13.1.8 (2022.1.12f1), 14.0.3 (2022.2.0b3), 15.0.0 (2023.1.0a4)
Couldn’t test with: 10.10.0 and lower because it doesn’t auto-generate the Reference field.

Reproducible on: macOS 12.5