VI Editor is not properly working and getting special character while moving my mouse here and there

Linux Basics Course
#1

VI Editor is not properly working and adding extra special character while while moving my mouse in the below file. I am not sure why it is behaving like this. Please advise and help. Thanks!

Topic : The Client Demonstration
Task 5 : Add an entry host “all all 0.0.0.0/0 md5” to the end of the file /etc/postgresql/10/main/pg_hba.conf on the DB server.

sudo vi /etc/postgresql/10/main/pg_hba.conf

#2

happens a lot. you can use the cat >> command.