In the last version of this mkp i added some line inside the readme.
!!! This package is obsolete please use the redfish package here
https://github.com/Yogibaer75/Check_MK-Things/tree/master/check%20plugins%202.2/redfish
!!! Starting with 2.3.0 the redfish package is also included inside CMK
Also the package has a version until set.
'version.usable_until': '2.3.0b1'
If you disabled the mkp then the error message is perfectly fine as you have hosts configured to use this special agent, but the special agent cannot be found anymore.
Solution: activate the mkp again - remove the rules for this special agent - deactivate the mkp