Reproduction steps:

# Open the attached “BugTest1.zip” project
# Open the “Assets/Scenes/SampleScene.unity” Scene
# Select all of the Cube GameObjects in the Hierarchy window
# Enter “L(1,5)” into the Transform Component’s Scale’s 'X' field
# Observe the Cube GameObjects in the Game View

Expected result: All of the Cube GameObjects have their ‘X', ‘Y’ and ‘Z’ Scale values equal to one another (The GameObjects retain Cube shape)
Actual result: The 'X’ Scale value is not “1”, but 'Y' and ‘Z’ Scale values are set to “1”(Some of the Cubes turn into Cuboids)

Reproducible with: 2021.3.16f1, 2022.1.24f1, 2022.2.2f1, 2023.1.0a25
Couldn’t test with: 2020.3.44f1 (“Constrained Proportions” option is not available)

Reproducible on: Windows 10 (21H2)