php artisan --version

Install PHP: sudo apt install software-properties-common ca-certificates lsb-release apt-transport-https
LC_ALL=C.UTF-8 add-apt-repository ppa:ondrej/php
sudo apt update
apt install php7.4

Version check: update-alternatives --config php

Disable: sudo a2dismod php8.1
Enable: sudo a2enmod php7.4

service apache2 restart

Reference: https://bytexd.com/fix-laravel-return-type-of-illuminatesupportcollectionoffsetexistskey/