What's the biggest checkout friction you've seen with Instagram/WhatsApp-first brands?

We've spent the last few months talking to D2C founders who sell mainly through Instagram DMs and WhatsApp, and the same problem keeps coming up: customers are ready to buy in the chat, but the moment they're asked to "click here to pay" or fill a form, a chunk of them just go quiet.

Curious what others here have seen — is it the extra app switch, trust in the payment link, or something else entirely? And for anyone who has fixed this, what actually moved the needle: faster replies, payment inside the chat, something on the catalog/pricing side?

Would love to compare notes with anyone building for D2C/social commerce.