I am using a very simplified model here
Revenue = DAU X Impressions per DAU X CPM
1)DAU
Assumption Q4 DAU = Q3 DAU = 1.82bio. This is conservative given Q3 DAU was +12% yoy.
Even with this assumption, Q4 DAU will be +10% yoy.
2)CPM
CPM data is from https://revealbot.com/blog/facebook-advertising-costs/
As per revealbot data, FB Q4 CPM was +23% yoy. Q4 is the only quarterly +ve CPM yoy for 2021.
Alternate source of FB CPM also looks inline with the above
https://datastudio.google.com/u/0/reporting/9b7783e4-7b55-4840-93bc-3c9469f519c6/page/2UkNB
3) Impressions per DAU
Revenue growth = DAU growth X Impressions per DAU growth X CPM growth
Implied Impression per DAU growth from actual DAU and CPM growth
Assumption Q4 impressions per DAU growth = Q3 = 1.11
4) Q4 Revenue
Q4 Revenue growth = 1.10 (DAU growth) x 1.11 (Impressions per DAU growth) X 1.23 (CPM growth)
=1.50 or +50% yoy
I view DAU assumption conservative and Impressions assumption as reasonable.
If I assume Q4 DAU growth at Q3 DAU growth rate of 12% then Q4 revenue growth is +53% yoy.
5) Massive beat looks likely
+50% Q4 revenue growth is double the current estimate of 25%.