Access error when run xtrabackup Failed to connect to MySQL server: DBI connect

Hello, I have the following error while try to run xtrabackup on AWS ec2 host:

[talexey@ip-10-6-14-72.us-east-2.compute.internal (aws_main) lib]$xtrabackup --backup --host=dvspinm1.prod.ch4.s.com --user=back_user -password=XXX --port=3306 --socket=/opt/mysql/SPINM1/mysql.sock --target_dir=/home/talexey
xtrabackup: recognized server arguments:
xtrabackup: recognized client arguments: --backup=1 --host=dvspinm1.prod.ch4.s.com --user=back_user–password=* --port=3306 --sot-dir=/home/talexey
200211 03:50:38 version_check Connecting to MySQL server with DSN ‘dbi:mysql:;mysql_read_default_group=xtrabackup;host=dvspinm1.p/mysql/SPINM1/mysql.sock’ as ‘data_owner’ (using password: YES).
Failed to connect to MySQL server: DBI connect(’;mysql_read_default_group=xtrabackup;host=dvspinm1.prod.ch4.s.com;port=3306;mysql_a_owner’,…) failed: Access denied for user ‘back_user’@‘ip-10-6-14-72.us-east-2.compute.internal’ (using password: YES) at - li
200211 03:50:38 Connecting to MySQL server host: dvspinm1.prod.ch4.s.com, user: back_user, password: set, port: 3306, socket: /op
Failed to connect to MySQL server: Access denied for user ‘data_owner’@‘ip-10-6-14-72.us-east-2.compute.internal’ (using password:

I can connect to MySQL from this ec2 machine:
[talexey@ip-10-6-14-72.us-east-2.compute.internal (aws_main) ~]$ !my
mysql -uback_user -pXXX -hdvspinm1.prod.ch4.s.com
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 497711339
Server version: 5.6.34-log MySQL Community Server (GPL)

Copyright © 2000, 2020, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.

mysql> select @@socket;
±-----------------------------+
| @@socket |
±-----------------------------+
| /opt/mysql/SPINM1/mysql.sock |
±-----------------------------+
1 row in set (0.01 sec)

I also can run mysqldump without any issues on this ec2 instance.

MySQL version: 5.6.34

xtrabackup --version
xtrabackup: recognized server arguments:
xtrabackup version 2.4.18 based on MySQL server 5.7.26 Linux (x86_64) (revision id: 29b4ca5)

Can you please let me know why do I have this error?
Thanks,
Tanya

Can I just check if this is an error in setting up a new backup, or an error that has started appearing when it was previously working fine?
thanks!