@RoshanS16889177 The error "Import failed due to an unallowed type change ALTER TABLE" during code migration can occur when the schema for externally mapped tables has restrictions that are not known in the rules. For example, if the length specified for a text column does not match the length in the property rule. To prevent this, ensure that the property definitions match the table columns as closely as possible, or use a validate rule that enforces the same restrictions as the schema.
If the package you are moving contains Database table Schema that contains changes like (EX: id - which is text in one environment and integer in another environment) like changes will not be deployed. First, we need to Change the column. Type manually in DB side then if we deploy the package through deployment manager or through by manually column type will be changed.
Note: Initially optimization of property and moving from one environment will be done. After if we want to change column type, we need do manually in DB side. Column length will be increased at any point of time.