Perhaps an overcomplicated constraint expression that compares the result of a Boolean expression with a Boolean value

Copy SQL

WITH expressions AS (select 
n.nspname as schema,
c.relname || '.' || o.conname as name, 
substring(pg_get_constraintdef(o.oid),7) as expression,
'TABLE CHECK' AS type
from pg_constraint o inner join pg_class c on c.oid = o.conrelid
inner join pg_namespace n on n.oid=c.relnamespace
where o.contype ='c'  
and n.nspname not in (select schema_name
from information_schema.schemata
where schema_name<>'public' and
schema_owner='postgres' and schema_name is not null)
union select n.nspname as schema,
t.typname || '.' || o.conname as name, 
substring(pg_get_constraintdef(o.oid),7) as expression,
'DOMAIN CHECK' AS type
from pg_constraint o inner join pg_type t on t.oid = o.contypid
inner join pg_namespace n on n.oid=t.typnamespace
where o.contype ='c' and n.nspname not in (select schema_name
from information_schema.schemata
where schema_name<>'public' and
schema_owner='postgres' and schema_name is not null))
SELECT schema, name AS object_identifier, type AS object_type, expression AS suspected_expression
FROM expressions
WHERE expression ~*'is[[:space:]]+(not[[:space:]]*)*(true|false|unknown)'
OR expression ~*'[)][[:space:]]*(=|>|<|>=|<=)[[:space:]]*(true|false|unknown)'
ORDER BY schema, type, name;