I am pretty sure the console creates suspicious migrations. Here a the reproductible steps:

• Start with a fresh Hasura instance & a fresh database as well;
• Set up a project directory & Open the console from the CLI (as show in the documentation);
• Create a table test with a ts column, selecting Timestamp as the type (and not Time, time without time zone nor timestamp without time zone). Use ts as the PK. You shoud see the following migration now:

CREATE TABLE "public"."test"("ts" timestamptz NOT NULL, PRIMARY KEY ("ts") );

• Edit the ts column, change its GraphQL field name & save. Now you will see the following suspicious migrations:

ALTER TABLE "public"."test" ALTER COLUMN "ts" TYPE timestamp with time zone;
ALTER TABLE "public"."test" DROP CONSTRAINT "test_ts_key";

Hope this report will lead to a better product!