Starcraft II Community API returns "Downstream Error" most of the time

Some endpoints seem to work consistently, like /sc2/static/profile/:regionId. But others, like /sc2/ladder/grandmaster/:regionId or /sc2/legacy/profile/:regionId/:realmId/:profileId/matches return “Downstream Error” about 9 times out of 10.

Two days ago things were working consistently, but since yesterday it’s barely usable.

Trying to visit my profile page usually results in a 404 too, although, again, not always: