The trackpad click is unresponsive after screen unlock on MacOS Catalina on MacBook Pro 2018
ajay. 

Do you already have the latest version (10.15.4)? If not, try to update, if yes, try the following: 

1) Reset your Mac's NVRAM or PRAM. 

2) If you continuing experiences issues, try to reset the SMC of your Mac.

I hope that works.