I fixed it by copying the Exim 4.95 template file!
→ Cant recive emails but can send - #6 by eris
I created a bug report on Github for this: [Bug] Cannot receive Mails anymore after Update Hestia to 1.9.1 and afterwards Ubuntu Upgrade from 22.04 to 24.04 · Issue #4758 · hestiacp/hestiacp · GitHub