Nah, most of USDT is on TRC20 because gas fees are way cheaper there and most of the exchanges support withdrawing USDT using TRC20.
So all arbitrageurs, market makers, etc, transfer USDT between different entities through TRC20 network. USDT on TRC20 started to increase only after Ethereum gas fees got ridiculously high and it became too expensive to use even for pretty high volume market makers.