I happened to find that there may be an I18N issue (maybe not) when granting permission on a SharePoint Online site.
My Windows 10 system is Chinese.
My SharePoint Online site is English.
When I when to site permissions to grant permission, I found there is a Chinese word in the permission level list. Please find the attached picture.
I think it may be caused by I18N way, a few of words depend on Window System culture. So just for your information.