Fetch records from table with value but not b

You can use NOT EXISTS (<subquery>). For example:

select uuid
from my_table a
where status = 'error'
  and not exists (
    select 1 from my_table b where b.uuid = a.uuid and b.status = 'ok'
  )

Or, you can use an anti-join:

select uuid
from my_table a
left join my_table b on b.uuid = a.uuid and b.status = 'ok'
where status = 'error'
  and b.uuid is null

If you have only two statuses, you may use aggregation with one table scan:

select uuid
from a
group by uuid
having min(status) = max(status)
  and min(status) = 'error'

| UUID                                 |
| :----------------------------------- |
| 082324d0-24a6-47ca-9b55-94fad628903e |

Or with conditional aggregation that may be extended to more statuses:

select uuid
from a
group by uuid
having count(decode(status, 'error', 1)) > 0 /*Has 'error' status*/
  and count(nullif(status, 'error')) = 0 /*And has no other statuses*/

| UUID                                 |
| :----------------------------------- |
| 082324d0-24a6-47ca-9b55-94fad628903e |

db<>fiddle here

Best approach (in terms of performance) would be to use analytical function.

SELECT UUID FROM (
  SELECT t.UUID UUID,
      t.status status,
      ROW_NUMBER () OVER (PARTITION BY UUID ORDER BY status DESC) status_rnk
  FROM  table t)
WHERE status = 'error' AND status_rnk = 1;