We have upgraded our Magento store recently from 2.3.5 to 2.3.7-p3.
After that we found your onestepcheckout is not working with Braintree Paypal express as the button Place Order is not hiden. If we disable your onestepchecout extension it works fine.
Please let me know if there is any patch you can share to fix it.
To fix this error, please edit the 2 files below: