Hi,
As we noticed the announcement of "API Integration Changes" - MD5 Hash Removal/Disablement.
The link we found https://developer.authorize.net/api/upgrade_guide/
in that HTTP GET STATUS: End of Life. in that it is showing alternate solution link to call API as bellow.
https://developer.authorize.net/api/reference/
Let us know does we need to do any changes in plugin code to call API for the changes of MD5 Hash Removal/Disablement.