Um… that’s an instance thing. Many instance disables downvotes to promote positivity. If you made an account on lemmy.world, you could actually downvote, just not if you are from an instance which disables downvotes. (your instance lemmy.blahaj.zone has disabled downvotes)

Edit: On the browser ui, the downvote button is actually not even shown when viewed from lemmy.blahaj.zone but some apps still show it for some reason.

Edit 2: Here’s a screenshot shown from lemmy.world, where the community is hosted: