See this thread on enwiki VPT for background.
When I load either of:
https://en.wikipedia.org/wiki/File:Young_Folks%27_History_of_Rome_illus090.png
https://commons.wikimedia.org/wiki/File:Young_Folks%27_History_of_Rome_illus090.png
The thumbnail shows with a broken image icon. In my browser console, I get:
Request URL: https://upload.wikimedia.org/wikipedia/commons/thumb/a/a1/Young_Folks%27_History_of_Rome_illus090.png/120px-Young_Folks%27_History_of_Rome_illus090.png Request Method: GET Status Code: 429 Remote Address: 208.80.153.240:443 Referrer Policy: origin-when-cross-origin
content-length: 1821 content-type: text/html; charset=utf-8 date: Wed, 30 Jun 2021 15:11:20 GMT nel: { "report_to": "wm_nel", "max_age": 86400, "failure_fraction": 0.05, "success_fraction": 0.0} permissions-policy: interest-cohort=() report-to: { "group": "wm_nel", "max_age": 86400, "endpoints": [{ "url": "https://intake-logging.wikimedia.org/v1/events?stream=w3c.reportingapi.network_error&schema_uri=/w3c/reportingapi/network_error/1.0.0" }] } server: Varnish server-timing: cache;desc="int-front", host;desc="cp2040" strict-transport-security: max-age=106384710; includeSubDomains; preload x-cache: cp2040 int x-cache-status: int-front x-client-ip: 69.115.77.204