On 2023-05-25, for approximately 15-20 minutes (~14:08 - ~14:27 UTC), logged in users connecting to to Wikimedia wikis through our Ashburn datacenter, and editors in general (approximately 7000 requests/s) may have received 503 errors or experienced higher latency than usual. Edit activity stopped almost completely.
The issue was mitigated and an investigation is ongoing to prevent the issue from reappearing. More info and details to come soon in the form of an Incident Document: https://wikitech.wikimedia.org/wiki/Incident_status
The ongoing status was kept updated at https://www.wikimediastatus.net/incidents/lx0vwl2p01xd (now resolved)