Same issue here – Square Payment Failed (Status code BAD_REQUEST: INTENT_MISMATCH).
The error only happens to small percentage of users. I’m using the following versions: WP 5.4, WooCommerce 4.0.1, WooCommerce Square 2.1.1.
I’ve rolled back to an earlier version of the Square plugin version 2.0.8 and will see if this prevents the issue from happening again.
