Steps to replicate the issue (include links if applicable):
Go to https://www.mediawiki.org/wiki/Special:Version
What should have happened instead?:
Tables with multiple captions should be separated and every table should be given its own <caption>:
- <tr><th colspan="5" id="sv-credits-specialpage">Special pages</th></tr> + <caption id="sv-credits-specialpage">Special pages</caption>
(id might also be moved to the <table> tag for simplicity)
- <tr class="sv-space"><td colspan="5"></td></tr> + </table> + <table class="…">
This might introduce a small misalignment between the nearby tables but, frankly, that is less of an issue than a WCAG violation.
Another good thing would be to add scope="col" on all table headers remaining:
- <th class="mw-version-ext-col-label">Extension</th> + <th scope="col" class="mw-version-ext-col-label">Extension</th>
Maybe upon a closer review from other accessibility-minded people there might be other issues.
Other information (browser name/version, screenshots, etc.):
Prompted by reading a comment in T363726: ?action=info should have a Table of Contents and looking into the code.