I have theses rules:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule materia/([^/]+)/?$ article.php?slug=$1 [QSA,NC]
RewriteRule busca/?s=([^/]+) search.php?s=$1 [QSA,NC]
RewriteRule ^([^/]+)/?$ index.php?slug=$1 [QSA,NC]
</IfModule>
But the second rewrite rules is not being applied when the URL is something like http://website.test/busca/?s=teste
htaccess tester: https://htaccess.madewithlove.be?share=28e2b25d-f6ef-5faa-a5c6-a412a87d5523