I just had to face the same kind of issue with my Laravel 7 project, in Debian 10 shared hosting. I have to add RewriteBase /
to my .htaccess within /public/ directory. So the .htaccess looks a like
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^.*$ /index.php [L,QSA]