NULL handling in 1D array comparison

postgres=# select version();
                                                             version
---------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 13.0 (Ubuntu 13.0-1.pgdg18.04+1) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0, 64-bit
(1 row)

Comparison should return UNKNOWN but it's returning a true. 

postgres=# select array[null]=array[null];
 ?column?
----------
 t
(1 row)

postgres=# select array[1, null]=array[1, null];
 ?column?
----------
 t
(1 row)

SQL-99 standard use to say it should come out as UNKNOWN

https://crate.io/docs/sql-99/en/latest/chapters/10.html#comparison