There is a list here: https://miningpool.observer/missing and a rather noisy RSS feed https://miningpool.observer/missing/feed.xml.

There's also an RSS feed with showing OFAC sanctioned transactions here: https://miningpool.observer/template-and-block/sanctioned-feed.xml (currently empty because I switched to a new database). In the past it alerted me about F2Pool censoring OFAC sanctioned transactions. See https://b10c.me/observations/08-missing-sanctioned-transactions/