https://es.wikipedia.org/api/rest_v1/page/summary/Manuel_Belgrano
The underlying Wikidata item was vandalized and then the vandalism reverted on June 11. The public summary endpoint for eswiki still shows the bad description, "pornstar argento".
Prod MCS returns the correct description (verified on scb1001).
The public endpoint returns the bad description even after a Varnish purge.
Therefore it seems like we're stuck with a bad summary stored in RESTBase and not updated after the reversion.
This shows up in the Android app but interestingly not the iOS app (maybe it still gets descriptions from mobileview).