Previously broken, too:
T93041: Some wikitech.wikimedia.org thumbnails broken (404)
https://wikitech.wikimedia.org/wiki/Deployments
contains use of https://wikitech.wikimedia.org/wiki/File:Yes_check.svg
I've tried purging the page and making null edits but the thumbnail remains 404 Not Found
GET https://wikitech.wikimedia.org/w/images/thumb/f/fb/Yes_check.svg/36px-Yes_check.svg.png
HTTP 404 Not Found