Mail.app on battery power messages are empty
When using mail.app (Big Sur - v.11.2.3, Mail Version 14.0 (3654.60.0.2.21) on battery power, the content of a mail is empty.
After ending Mail and restarting the app, the message shows properly. I do not have this problem when the MacBook Pro is plugged in.
Has anyone seen the same problem/issue?
MacBook Pro 13″, macOS 11.2