Outlook sending emails into spam folder

Hello, is there any new updates or anything going on, I got two separate customers that are G Suite customers that use Outlook 2010 / 2019 and I am getting a few users that are saying they are starting to get normal emails going into their spam folder. Some of the emails are from users organization and in their contact list but something is starting to send more emails into the spam folder, I am wondering has Outlook done some sort of update or is something else going on or by chance more than one customer is experiencing the same problem?