I’m an admin of my own instance and I have direct access to the database.

On the database I run these two queries:

For comments:

select p.actor_id, c.content
from person p
         inner join comment_like cl on cl.person_id = p.id
         inner join comment c on cl.comment_id = c.id
where cl.comment_id = ?
  and cl.score = -1;

For posts:

select p.actor_id
from person p
         inner join post_like pl on p.id = pl.person_id
where pl.post_id = ?
  and pl.score = -1;

You can replace the question mark with post/comment id.