A bunch of money left the market from Grayscale, some money got traded from Grayscale to other ETFs, and a bunch of new money came into the market through ETFs. Of the billions of dollars that actually left the market from Grayscale (was not simply moved to other ETFs), that selling had to be absorbed by the already existing spot market as well as the new money flowing into the other ETFs.
there are two ways of exiting fiat from having grayscale shares
A. just buying and selling shares within grayscale to play Nav within grayscale and get fiat from other grayscale traders by selling shares
(this is seen by the "volume" of trades in grayscale(does not affect grayscales coin holdings))
B. purchasing/having baskets worth of shares to then request share dissolving/redemptions to then get fiat via coinbase after coinbase unlocks BTC to sell BTC to spot market/otc market.
(this is seen by the dilution of coins custody total)
when you see how much coin dropped out of grayscale and how much coin accumulation other ETF have you can see pre-post basket redemptions where the coins ended up
even when getting fiat to pay down the FTX claim. that was (b). not (a)
but when DCG handed FTX the fiat after coinbase sold the coin... other ETF AP were on the buying side of that coinbase sell off to accumulate those coin to put into ETF
coinbase did not have a hoard of fiat to give DCG to then pay FTX. the fiat came from other ETF AP wanting to buy baskets of coin