CSS background property showing under invalid.deprecated scope despite not being invalid/deprecated.

[Monstar]

Prerequisites

I don't actually use Atom so I haven't run some of the following:

• [] Put an X between the brackets on this line if you have done all of the following:
  • Reproduced the problem in Safe Mode: https://flight-manual.atom.io/hacking-atom/sections/debugging/#using-safe-mode
  • Followed all applicable steps in the debugging guide: https://flight-manual.atom.io/hacking-atom/sections/debugging/
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Description

Reported the issue on vscode, been told it has to do with this repo so i'm reposting it here.
The background property under transition is showing up under the invalid.deprecated.color.system.css scope, which makes it show up as an error.

Steps to Reproduce

1. Create a new css file
2. Add the following code

.test {
  transition: background;
}

Alternatively :

.test {
  background: white;
}
.test:hover {
  background: red;
  transition: background 2s;
}

3. Inspect editor tokens and scopes
4. Hover on background

Expected behavior:

Should not show as deprecated/invalid because the background property is animatable and not deprecated: MDN docs | W3C docs.

Actual behavior:

The background property under transition is showing up under the invalid.deprecated.color.system.css scope, which makes it show up as an error.

Reproduces how often:

100%

Additional Information

microsoft/vscode#150057