What is file suffix Malware?

Hello,

After upgrading to PHP 8, some websites stopped working due to malware that used a undefined function. Fortunately, I solved it by simply deleting the code. (see here)

However, files that have a malware suffix (such as www/​wp-config-sample.php.malware) remain on the websites.

Is this normal and can I delete these files, please?

Thank you