No issues on my accounts when I ran 17.1.1, .1.2 and 17.2 RC on iPhone 15 Pro. iCloud, Outlook.com and my Work Exchange account setup with the Mail app.
Check downdetector or your email service to see if there isn't an ongoing server issue. Turn off any VPN or PiHole, etc. you may be using and see if that solves the issue.
Lastly, if you think it's device related, try removing all your accounts, delete the Mail app, reboot. Download the Mail app from the App Store and re-add your accounts one by one.