USD Coin has indeed increased in use, although given the supposed liquidity of these two assets, you could wonder why the move doesn't happen far faster than it has...

Also there's a very interesting difference between USDC and Tether in terms of volume.

based on https://nomics.com/ Tether has a market cap of $62.85B and a 24 hour volume of $70.19B

USDC has a market cap of $23.90B and a 24h volume of $1.84B

So, for some reason, the velocity of Tethers is about 14 times higher than USDC, which seems unusual given they're nominally the same class of asset operating in similar markets.

The different volumes could reflect that folks have started to lose trust in Tether vs USDC, and so Tether is used as a big liquidity pool to move between different positions, but no one's endeavoring to hold big Tether positions for longer than necessary. Whereas USDC might be the preferred parking place when folks actually want to spend some time out of market without fully leaving the casino.

I don't know if that's actually true.

That seems potentially easy to explain given that some of the bigger (higher volume) exchanges support USDT and not USDC.

I know that was the case in the past, but is it still the case? from a 10 minute look, the 4 largest exchanges by volume (Binance, Coinbase, Huobi, and Kraken) all seem to list USDC

Hmm yeah maybe not, even Bitfinex trades USDC, and anyway they're a much smaller percentage of volume than I thought (jesus binance is huge).

Wonder if it's just network effect then? Big traders use the USDT markets because they're more liquid -> the USDT markets become even more liquid and the cycle continues.