If you use Outlook mobile at all, you could as well switch to O365 entirely, as Outlook Mobile will just take your login data an use an external Microsoft system to read all your mails. Nobody knows how this process could be made GDPR-compliant, plus it has the bonus that the external server continues to login to your accounts even if you delete the account in Outlook mobile (!). So please if you have any concern about data protection, just keep away from that app.
See details e.g. here:
https://borncity.com/win/2023/01/01/security-risk-microsoft-outlook-app-transfers-credentials-and-mails-to-the-cloud/
Not that this is a different issue from the discussion around the "New Outlook" that is currently being pushed to Windows users, which has similar problems.
HTH, Jakob