@ruchin78 how about if you try the chown commands without the user group like so…also, are the paths/user in the following steps the same as yours?
sudo chown -R frappe /home/frappe/.bench
sudo chown -R frappe /home/frappe/frappe-bench
cd /home/frappe/.bench
git reset --hard
git pull
cd /home/frappe/frappe-bench
bench update