This affects all supported versions. To repro:

CREATE TABLE t (a INT PRIMARY KEY);
INSERT INTO t VALUES (1), (2);
ALTER TABLE t ADD COLUMN b FLOAT NOT NULL UNIQUE DEFAULT random();

Expected: SELECT b FROM t@t_pkey and SELECT b FROM t@t_b_key yield the same results.
Actual: they don't, this appears to be true for any volatile default expr.

Jira issue: CRDB-15179