I am writing this to let you know that we recently upgraded Magento from v2.2.5 to v2.3.5, while doing so Paypal package which also got upgraded is not working in the newer version.
We investigated this issue but couldn't' find any solution for the same, we suspect that the installed PayPal package in the 2.2.5 version, when upgraded to version 2.3.5, was not working in the newer version.
We installed a Magento 2.3.5-p2 application with which the Paypal package was installed and when checked it was working fine in the newly installed Magento application, but not working in the upgraded version and then we compared the codes with the upgraded version, and we are not able to find any code difference both packages.
We replace the upgraded PayPal code with a newly downloaded 2.3.5p2 Magento PayPal module then it working fine in our upgraded environment also.
Please provide us any solutions in this regard, to make this work.