Mail is immediately archiving new gmail messages!!

I have a similar problem. Seemingly, out of the blue, 3 weeks ago. I lost my entire Sent Folder within gmail. Finally found many of them in Archive. Also noted that new msgs sent go right to Archive.

Don't recall changing any Settings/Preferences. Could this have started with a MacOS Update? There have been problems before with a new Update being incompatible with gmail (until it's fixed).

How do I get things back to normal?

Yes, true.

Gmail has an All Mail folder, formerly know as Archive. As far as I understand, it is just a mirror of all of your normal email messages and not a duplicate, hence, if you delete emails from All Mail, then they are deleted in the actual folder they are stored in.

As Barney-15E has pointed out, and as far as I know, no other email providers work like this, and in personal experience, Gmail has many more account settings and options than other email providers provide which can make it more difficult, (Other than Exchange accounts, which can also prove complicated).

As far as Mac Mail is concerned, you can check out the available preferences, and account behaviors to make sure they are set as you need though:

Change Mailbox Behaviors preferences in Mail on Mac - Apple Support

Use rules to manage emails you receive in Mail on Mac - Apple Support

Hope you’re able to figure it out!

That's how Gmail works. Mail maps the All Mail label to the Archive folder. Gmail marks all incoming messages with both the Inbox and the All Mail labels, so every email appears to exist in two different folders. Since this is not a normal behavior for an IMAP email account, Mail will have trouble. It expects Gmail to act like a true IMAP server, which it isn't. Just because you told it to pretend it was an IMAP account doesn't make it an actual IMAP account.

Use Gmail's web portal. It was designed to work with all of Gmail's idiosyncrasies.

I need to use an email app on the computer for all my email addresses, so it needs to work there.

Then, I would suggest you find a different email client. I don't know of any that are specifically designed for Gmail.

You can disable the All Mail Label in IMAP in the Gmail settings, Labels. But, I have heard that newer Gmail accounts cannot do that. I don't know if that is true as I have an older account and can disable it.

However, if you use Gmail's feature of attaching multiple Labels to the same message, you will run into the same problems you see with All Mail.

I have not experienced that in my workflow.

I have many years used gmail and iCloud mail side-by side (now in Monterey). Outlook mail is separate and only used for emergencies.

Usually I check the primary gmail in Safari and it shows and preserves the gmail Inbox for new mail.

Mail.app shows both gmail and iCloud mail in its "All Inboxes".

I occasionally copy&move in Mail.app important inbox mail to 1. gmail's Remote mailboxes and also 2. Mail.app's "On My Mac > Local" mailboxes. So wherever I am, I can see the archived old mail back to 1990. It might be overkill to archive mail to two places, though.

Finally found many of them in Archive. Also noted that new msgs sent go right to Archive.

Sounds normal for Gmail. An “All Mail” label is added to every message so they can harvest everything.