Square hasn’t rolled out to all merchants. This is something new announced by PayPal as of today, rolled out to all US merchants. Are you describing this new rollout, or the approach they took a few years ago.
Discussion
The one Paypal announced today. That's how it works. According to this
https://fortune.com/crypto/2025/07/28/paypal-100-cryptocurrencies-accept-merchants-bitcoin-ethereum/