There is no technical difference between https://site.com and https://site.com/ and even if there was, search engines would be clever enough to recognise those as the same thing.
There may be a difference between https://site.com/folder/ and https://site.com/folder, however you already emptied the container_suffix and there’s also an automatic redirect by default if I recall correctly.
MODX expects the site_url to always end in a slash so I do recommend adding back the slash to avoid issues.