Same here. Saw it across multiple accounts this morning around 10 AM GMT - not just one campaign or one ad set, but a uniform drop in CTR and a spike in CPMs across the board. Ran a quick Screaming Frog crawl on the landing pages to rule out server-side issues, then pulled GSC data to check if organic traffic was also affected (it wasn't). So it's definitely a platform-side ad delivery problem.
I've got three separate ad accounts in three different verticals (FinTech, SaaS, e‑com) and they all took a hit at the same time. My working theory is Meta pushed a change to the auction algorithm overnight and it hasn't stabilised yet. If you check the "Delivery" column in Ads Manager, you'll probably see "Learning limited" on most ad sets that were previously in "Active".
Not panicking yet - historically these blips resolve within 24-48 hours. I'm just keeping a close eye on the frequency metric and pausing any ad sets that show a frequency >3 with a 20%+ drop in ROAS. Worth turning off any dynamic creative tests until the dust settles, too.
