All Junk & All Trash has disappeared on Big Sur

Sorry my question to you was unclear - my bad - I meant to determine if Apple Mail was using iCloud as the mail servers or some other mail servers - thus your reply is unclear to me.

Firstly in Apple Mail - are there any Nested Sub-folders. If not and using iCloud as mail servers - using Safari go to www.icloud.com and log in using iCloud ID and password. If using Other mail server do same only log into the Mail Servers with their credentials. Check and see if the Junk and Trash folders exist on their Server. If No - there is the answer - one will need to create these folder and then Sync Apple Mail

Hey there!

Thanks for the extra info! If I have this right. If you hover your cursor to the right of, say, “Favorites”, “iCloud”, “Smart Mailboxes”, etc. and click on the “+” sign, then add “Junk” or “Trash” by selecting it, do they then show up?

In mail, look at the sidebar. At the top, you'll see Favorites. Move the cursor to the right of the word Favorites until you see a + sign and click on it. Now you can add "all trash" and "all junk"

In the Apple Mail Application - upper left look to three horizontal dashes and click on it. Will open Mail Boxes below

Is the Apple Mail App using iCloud mail for some other mail server.

Do you use a Gmail / Google account?

No worries, I guess I left out the “All” part of it in my reply.