Reproduction steps:
{}{}1. Create a new project and make sure Editor is in dark theme
2. Open Animation window (Window > Animation > Animation)
3. Select any GameObject (e.g. Main Camera)
4. Press “Create” button in Animation window to create Animation Clip
5. Press “Add Property” button and add any of the Properties
6. Press on the circle icon on the newly added Property and select “Delete Key” option and observe
7. Press on the circle icon on the deleted Key Property and select “Add Key” option and observe

Actual result: Property name color changes and “(Default Value)” text gets added when Key is deleted and doesn’t change back when Key is added again
Expected result: Property name color changes and “(Default Value)” text gets added when Key is deleted and everything changes back when Key is added again

Reproducible with: 6000.3.0b1
Couldn’t reproduce with: 2021.3.56f1, 2022.3.66f1, 6000.0.58f1, 6000.2.4f1 (No “Delete Key” and “Add Key” options in Property button selection)

Reproduced on: Windows 11

Note:

• Undoing the change via keyboard shortcut or context menu solves the issue
• Issue is also reproducible by deleting and adding the Key itself, but only in 6000.3.X