If a new field is created, having a table relation, the field datatype/length is set. If the related table definition is changed, e.g. increase of related (key) field length from code 10 to code 20, the fields having a table relation should be increased as well.

Describe the solution you'd like:
Have a new CodeCop rule that checks any field having a TableRelation to match at least the MINIMUM length of the related field (cfr. test codeunit 134926 Table Relation Test)

Also see Github
https://github.com/Microsoft/AL/issues/4493