On my KuCoin tweet, showing Tether getting now a 300% APY interest rate, a lot of people have commented that it's only on a "limited" amount or that the fine print reduces it.
That's not the point.

Exchanges flashing 300% APY's is like when you get an email from a Nigerian prince, promising you fifty million dollars if you just help them move the money out of Nigeria... and the email is full of bad grammar and spelling.

The bad grammar and spelling is deliberate, because someone that figures out it's a scam from the spelling, would not fall for the scam if the grammar and spelling is good. They're not stupid enough.
You don't want to waste time trying to scam someone that will figure it out.

Exchanges are trying to lure in dumb money into the exchange, someone that is intelligent... reads the fine print.
They're trying to lure in as many suckers as possible. The exchange is desperate for new deposits, and are resorting to underhanded tactics.
Something is wrong.