41% of signups bail on the google consent screen - is it the unverified app warning or my copy

The warning is not 41% of your problem. Placement is.

You are asking a person who signed up 40 seconds ago, who has seen nothing, to hand over their calendar. Of course they stop. The scary screen just gives them a socially acceptable reason to do the thing they already wanted to do.

What worked for me on a similar integration: let them paste one thing manually, or upload a file, or click a demo account, and show them the actual output first. Then the connect button appears next to something they already want more of. Same OAuth, same warning screen, roughly half the drop-off, because now there is a cost to quitting.

Numbers from doing exactly this. My drop at the consent step was 38%. I added one interstitial page before the redirect: a screenshot of the actual Google screen they are about to see, an arrow pointing at the advanced link, one sentence saying this is what an app looks like before Google finishes reviewing it, and a line naming the single scope I request and what I do with it.

Drop went to 19% over the next 300 signups. Cost me an afternoon. The verification itself took several weeks of back and forth over the demo video and the privacy policy wording, and during that whole time the interstitial was carrying the product.

Do the interstitial first. It is the cheapest thing on this list.

Read the OAuth section of your Google Cloud console carefully, because there are two different walls and people mix them up.

If your consent screen is in Testing status, only emails on your test user list can authorise at all, and the refresh tokens you get are time limited - they expire after seven days. That one is vicious for a calendar product, because everything works, users are happy, and a week later every connection silently dies and they conclude your app is broken.

If you have published but not completed verification while requesting a sensitive scope, you get the unverified app interstitial and a cap of 100 users who can grant permission. Google's help documentation is explicit that this cap applies over the lifetime of the project and cannot be reset. Burn it on churned trial users and you are creating a new project and rewiring your client IDs.

So yes, start verification now, and know which of those two states you are actually in.

Two separate reviews exist. Brand verification, which is the lighter one that lets your name and logo show on the consent screen, and sensitive scope verification, which is the heavier one with the demo video and privacy policy review. Do not conflate them when you are estimating time.

Also record the demo video before you think you need it. Google wants to see the actual consent flow and what happens with the data afterwards, on the domain you registered, with the OAuth client you submitted. I got bounced twice - once because the video showed localhost, once because my privacy policy did not name the scope in plain language. Each round trip cost me about two weeks of calendar time and about 20 minutes of real work, which is the most annoying ratio in this whole business.