The enwiki_p replica on s1 appears to be corrupt. The pagelinks table contains links that no longer exist on the live wiki.
Example (just one of many I could demonstrate):
https://en.wikipedia.org/w/api.php?action=query&list=backlinks&bltitle=KIFM&blnamespace=0&format=jsonfm shows that there is only 1 article linking to the title "KIFM" as of now.
On Tool Labs, the database query copied below returns 220 rows, even though replication lag is currently around 1 second:
MariaDB [enwiki_p]> select page_title from page join pagelinks on pl_from = page_id where page_namespace=0 and pl_namespace = 0 and pl_title="KIFM";