[Unknown error when running a simple bash script]

[avni]

Configuration Information [Automatically generated, do not change]:
Machine: x86_64
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -g -O2 -flto=auto -ffat-lto-objects -flto=auto 
-ffat-lto-objects -fstack-protector-strong -Wformat -Werror=format-security 
-Wall 
uname output: Linux asus-laptop.example.com 5.15.0-27-generic #28-Ubuntu SMP 
Thu Apr 14 04:55:28 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Machine Type: x86_64-pc-linux-gnu

Bash Version: 5.1
Patch Level: 16
Release Status: release

Description:
        [I am trying to run an if loop in my script and the if loop has a 
conditional statement, if [[ $input == "y" ]]; then echo "Some text". 

When I am running the script, it says "[[: not found."

Please let me know the solution of this problem.