This is a known bug, reported here.
You could add a comment to that bug, saying it is a problem for your phone too. (It was originally reported as affecting a Fairphone, but it has been reported against at least one other type of phone as well)
[Edit] There may be a [problem or problems in the K-9 Mail app on which the /e/ Mail app is based. Some of these are fixed in more recent K-9 versions, but those fixes have not been pulled into the /e/ version.
This is one of the reasons why I use the upstream K-9 app instead of /e/'s fork. (It’s also loads better IMHO for working with multiple email accounts, each gets their own colour.) It’s available in F-Droid , Apps or Aurora Store. You can export your account settings from Mail (‘three dots’ menu | Export Settings and accounts) and import them to K-9 when you first run it after installing (or later from the settings menu).