How often do file permissions get reset?

ANSWER: File permissions, including owners, groups, and file/directory permissions in Linux Ubuntu are reset via cron jobs every 1 hour. Similar cloud VPS hosts opt to reset these only once per 24 hours, but since we put each site on its own VPS server, we can push this window a bit faster. Please understand that you can avoid all file permissions issues but avoiding over relying on SFTP usage and editing CSS/files via the WP Admin panel whenever possible.

https://www.littlebizzy.com/services/permissions-reset