No messages appear in my Trash or Junk folder

Hello KS_on_AS,

Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with mail not going to the trash or junk folders in the Mail app. To start, have you tried searching for a specific email that was affected to see if it appears in another folder? Do they show up in the correct email boxes when you check the webmail version of the affected accounts?

Also, try the steps here to see if they resolve the issue by removing and adding an affected account: Add email accounts in Mail on Mac - Apple Support

"Use the Mail app  on your Mac to send, receive, and manage email for all of your email accounts in one location on your Mac. Simply add your existing accounts—such as iCloud, Exchange, Google, school, work, or other—in Mail.

• The first time you open Mail, you may be asked to add an account. Select an account type (such as Google for Gmail) or Other Mail Account, then enter your account information.
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• If you already added an email account, you can still add more. In Mail, choose Mail > Add Account, select an account type, then enter your account information. Make sure the Mail checkbox is selected for the account.
• If you’re using an account on your Mac with other apps, such as Contacts or Messages, you can also use that account with Mail. In Mail, choose Mail > Accounts to open Internet Accounts settings, then click Add Account on the right.
• You can set options for your email accounts in Mail settings."

We hope this helps.

Cheers!