Hi Terry. I'm Greg, an installation specialist and 8 year Windows MVP, here to help you.
The Mail app will occasionally have you sign into the Account again depending on what the provider requires. Questions about this are best directed to the provider who always include Support for email in your monthly bill because it's one of the things their customers need the most. In my experience after 9 years daily in forusm, those who don't use the provider's accounts but use a purely webmail account like Outlook or Gmail generally have less problems.
One thing you can try that often helps is deleting the account in Mail Settings (gear icon at bottom of Inbox) > Manage Accounts > SBC account > Delete account, then restart the PC and add it back. Since it's only a sync service and doesn't actually store mail or folders this is easy and often solves problems.
If not you can reset the Mail app at Settings > Apps & Features > Mail and Calendar > Reset.
If you want to report this to Microsoft use the Feedback Hub app in Start Menu where developers are tasked to process consumer feedback. But Microsoft will not even see it here because this is a tech forums where we are mostly volunteers trying to help solve your problems.
I hope this helps. Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.