Deprecation is…
status applied to features, characteristics, or practices to indicate that they should be avoided, typically because they have been superseded.
In other words, attribute_escape has been replaced by esc_attr.
Any time you use a deprecated function WordPress triggers the error you’re seeing. Somewhere in your codebase a deprecated function is being used.
To fix the error, you need to locate where attribute_escape is in your code. It won’t be in the WordPress core as deprecated function calls are removed.
So, search your entire wp-content directory for attribute_escape. When you find it, replace it with esc_attr. I would use the command like ack-grep for this.
$ cd /path/to/your/wordpress/install/wp-content
$ ack-grep attribute_escape
But any filesystem search will probably work just fine.