As of api portal v4.2.1, only 254 characters are allowed for Template Attribute Fields, Api custom fields, App custom fields. @54 chars are too short. We want more characters are allowed for Template Attribute Fields, Api custom fields, App custom fields, such as 4k characters
From the documentation regarding custom fields for example in link below
You looking for the Maximum length to ge expanded to 4k ?
Defines the name for the field you are adding.
Maximum length: 255
Request is FROM
DFS CORPORATE SERVICES LLC
Support issue 20065214