This was flagged by a recent Lighthouse audit, and may affect Google Search due to being included by PageSpeed Insights and Search Console as of last year.
I've confirmed against production page views that the navigation element indeed points to minerva-user-menu-toggle but there appears to be no id="minerva-user-menu-toggle" element in the HTML.
- Visit https://en.m.wikipedia.beta.wmflabs.org/wiki/Barack%20Obama in Google Chrome
- Open developer tools and click audit tab
- Under audits make sure only accessibility is checked
- Click "run audits"
- In the report there should be no mention of "[aria-*] attributes do not have valid values". The score should be higher than or at least equal to 93. Please report here with the score.