==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): latest
- Linux/BSD distribution name and version:  debian
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):  mysql
- Web server (Apache or Nginx): apache
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

COMMAND:
curl --verbose --insecure --url "imaps://$serwerpoczty/INBOX/" --user "$login:$pass" -X "UID MOVE $id Trash; EXPUNGE;"

GETS ME:
< A002 OK Logged in
> A003 SELECT INBOX
< * FLAGS (\Answered \Flagged \Deleted \Seen \Draft NonJunk)
< * OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft NonJunk \*)] Flags permitted.
< * 1 EXISTS
< * 0 RECENT
< * OK [UIDVALIDITY 1515605811] UIDs valid
< * OK [UIDNEXT 1019] Predicted next UID
< A003 OK [READ-WRITE] Select completed (0.000 + 0.000 secs).
> A004 UID MOVE 1 Trash; EXPUNGE;
< A004 NO [TRYCREATE] Mailbox doesn't exist: Trash; (0.000 + 0.000 secs).
> A005 LOGOUT
< * BYE Logging out

On other server it works...
I checked - the Trash folder exists.