Additional Z* field Update Rule is getting created For some Target Tables

Hello Everyone,

System is creating additional z*  field update rule for some target tables. For example in Material master I have created target tables for MARA, MAKT, MARC and out of which additional zMATNR field update rule got created for MAKT and MARC target tables and that too with some issue as shown below,

What is the purpose of this rule and how to avoid this error in the rule while system is creating this rule?