[Broken Website] Inline CSS text appears in datetime for a merged pull request on GitHub #15580

Prerequisites

• I searched for any existing report about this website issue to avoid opening a duplicate.
• I can reproduce this website issue in a new, unmodified web browser profile with Dark Reader installed as the only extension.

Website Issue Description

When Dark Reader is enabled on a merged pull request (enabled before going to the page, or when you refresh), the supposed "date and time" element's #shadow-root (open) gets replaced with Dark Reader element tags and supposedly a duplicate of the darkreader--inline style.

Website Address

https://github.com/[creator]/[repository]/pull/[id]

Steps To Reproduce

1. Go to any repository's pull requests page.
2. Filter the pull requests by "Closed", then select a request (preferably one with a lot of comments, so you can properly see the bug in action).
3. Scroll down to show the title bar that appears normally.

Expected Behavior

The text next to the "Copy" icon (<relative-time datetime="">) should display how long ago since it was merged, or nothing (I have no clue if it shows normally or not since I tested it on multiple requests and that element usually shows nothing).

Actual Behavior

The text is replaced with Dark Reader's CSS formatting in plain text within the #shadow-root (open) element of relative-time, including the plain text string duplicated from the darkreader--inline style.

Screenshots

Operating System

Windows 11 Home (25H2)

Web Browser name and version

Opera GX 131.0.5877.111

Dark Reader version

4.9.125

Additional Context

This doesn't appear when Dark Reader is disabled on the website — only when it is enabled.
If enabled, it persists if you disable it (until you refresh the page).
This can happen on any browser (tested on Chrome, works there too).