The following query wraps JSON from a derived table in more JSON:

select json_array(`v1`) from (select json_array(1) as `v1`) as `t`

This results in undesirable output:

["[1]"]

It doesn't happen with scalar subqueries:

select json_array((select json_array(1) as `v1`))

Or with the usual laborious workaround for such problems:

select json_array(json_merge_preserve('[]', `v1`))

from (select json_array(1) as `v1`) as `t`

Both resulting in the expected output

[[1]]

For comparison, MySQL 8.0.22 doesn't behave this way.