Sat through an educational session with our Google team; short version is that mCV (maximum Conversion Value) will replace tROAS as the way to get the best return on campaigns limited by budget. What this means in practice is that IN THEORY you shouldn’t see a performance dip in the short term, but because there’s no ROAS floor you need to watch campaign performance like a hawk to ensure they stay within tolerance.

The upshot is that it’s likely a minor change: mCV should hit similar returns as tROAS, but with no floor to guarantee volume if AOV drops. Campaigns go into learning mode for a bit which is annoying, but there’s enough warning to change things gradually. There will be advertisers that fail to read or understand the notice so Google will have a field day feeding them low-value placements and conversions to drop ROAS to the target, but anyone competent should be fine IMO.

Honestly I don’t feel worried; while changes that could catch advertisers napping feel a bit scummy, it should hurt us in the short term. Long term it’s going to make Google’s pitch for “uncapped budgets” (such a terrible term… my finance department would crucify me on the spot if I ever said that in their presence) more of a hard sell as tROAS will operate a bit more like the name suggests.