User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/113.0

Steps to reproduce:

1. Open the Inspect Element tools using F12
2. Select/focus any element that has some CSS (for example the background color) with the 'Pick an element' tool.
3. Change the CSS (for example the background color) of said element in the dedicated CSS edit/view tab.
4. Go to 'Changes' tab on the right and note your changed/diff CSS being there.
5. Exit out of the Inspector by pressing F12 again or clicking the x on the top right.
6. Re-open the Inspector and go to the 'Changes' tab if not already open.
7. See that 'No changes found' in the 'Changes' tab despite the CSS of the website still being modified.

Actual results:

The 'Changes' tab forgot about the locally changed CSS and declares 'No changes found' when closing and re-opening the Inspector.

Expected results:

The 'Changes' tab inside the Inspector should still contain the previously locally changed CSS when the website hasn't been refreshed even if the Inspector closes and re-opens.

The Bugbug bot thinks this bug should belong to the 'DevTools::Inspector' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Thanks for filing, this looks like a duplicate of Bug 1542679