Do you have an opinion on why it's rating badly?
Further, I saw a few tweets which also agreed with me regarding the cast. I also think the cast picked up in leg two (like other tweets agreed) and have picked up then.
TV ratings, especially live TV ratings, have been on a consistent decline since the start of the US 'Amazing Race' and to get into the minutiae of the reasons why (demographic shift, cord-cutting, live-to-extended viewing, etc. etc.) isn't going to solve much of anything. If the network feels they get enough out of it for short and long-term viewership, justifies the advertising revenue, has the sponsors to back prizing, and keeps the cost of the show low ('The Amazing Race' costs a bit more than a couple bucks to make, but it's a drop in the bucket compared to both scripted shows and other reality shows), then they'll keep it going. Or they won't and it'll shop elsewhere-- as they've done-- and it'll happen somewhere else. 'The Amazing Race' is a known reality brand and, for all intents, a staple in the canon.
Comparing it to TAR AUS 5, which took place during the pandemic when, for when it was aired, everyone should have hypothetically been home watching it, isn't going to be a strong reflection. The difference between then and now is the difference between quarantine/lockdown and, for all intents, an open world.
General viewers aren't looking at the destination list and thinking 'oh I'll watch this because I like Morocco and Greece'. If that was ever why people were picking up TAR in the first place, they would have been watching by now, and the network would've waited to do TAR AUS 5 internationally.