Looking up the USDT rate for Telegram Stars doesn't require a payment, a wallet connection, or any commitment — it's just a number to check.
A card charges a fixed fiat price instantly with no extra step; paying with USDT adds one extra step — checking the live rate first.
USDT rates can move within the minute it takes to complete a transaction on TRC-20 — the displayed quote is what's honored.
It's very close — NiceStars tracks the same market USDT is priced on.
A small spread covers TRC-20 fee volatility, so the rate can be marginally different from a spot exchange price.