Battery drain Pixel 8 pro Android 14

Hi all,
I previously used K9 for years with my OnePlus 6 without any issues. Now I updated to a Pixel 8 pro with Android 14.
I transfered all settings and accounts to the new phone. Unfortunately I have a huge battery drain caused by K9. Do you have any ideas what I can do to solve the issue?
I have 9 accounts, all with push IMAP to handle.
Your support is highly appreciated,