Text in mail replaced by question marks in boxes
I recently just opened my mail again and out of nowhere the text in all mails is replaced by question marks in squares. the preview on the left of the mail is normal text only if you open the mail the text is changed.
This also happens in internet pop-ups when I want to connect to a public WiFi.
I got no third party font manager and opened Font Book but I can't see ANY fonts in it. I scanned my MacBook with Bitdefender but don't have any virus.
MacBook Pro with Touch Bar