How Meta's A/B test splits the audience
Two ads side by side is not a test - the split is.
You build the two versions as separate ad sets or ads; the tool splits audience and budget evenly, which avoids the uneven spend of "faking a test by just running two ads." Meta "usually suggests around 7 days", allowing 1 to 30. Too short or too small and results "swing around randomly and tell you nothing." The tool does not enforce that versions differ in one thing only - "that is your discipline."
Valid answers instead of noise.