The amount of GTIN digits are changed by the system. The new GTIN does not get accepted, for example in iPhone.
SAP Cloud for Customer
Previously this issue was solved when customers changed the message severity and/or suppressed the message.
You can find the setting in your Business Configuration work centre --> Navigate to Fine Tuning Activities --> Find and open 'Materials' --> Select 'Message Severity Configuration'.
However, please make sure that your set-up is correct as per How to set correct EAN or GTIN numbers.
KBA , LOD-LE-PRL , Product List , Problem
SAP Cloud for Customer core applications 2202