failed to find conversion function from "unknown" to ...

Hello!

This query

select 1 where 'vasya' = (select 'vasya')

produces

ERROR:  failed to find conversion function from "unknown" to text

in my 8.0.0.

If I explicitly cast second 'vasya' to text, it is Ok.
Everything is fine if data comes from database, IOW
type is known.

Is what I am describing desired behavior?

Thanks.

--
Best regards
Ilja Golshtein