Here is how to disable inline attachment previews and view as icon when composing new mail
There are many open topics for this issue so here is the short and working solution for Mail, at least in OSX Monterey.
1: you need to give terminal full disk access, System Preferences > Security & Privacy > Privacy > Full Disk Access, add Terminal and check it to be active.
2: restart terminal
3: enter the following terminal code which is mentioned several times before, but with full disk access for Terminal it is actually working now:
defaults write com.apple.mail DisableInlineAttachmentViewing -boolean yes
4: restart mail. Create a new email and now attachments are in icons not that annoying embeds.
MacBook Pro
