Recently, I've seen people equate "an increase in stablecoin supply = a rally is coming" directly, which is a bit of an overinterpretation.

The increase or decrease of stablecoins often just reflects funds moving between off-chain and on-chain, or changes in market making and settlement needs, and doesn't necessarily correspond directly to market direction.
It's the same with ETFs; a net inflow looks good but doesn't mean the chain will immediately heat up.
Many funds simply don't plan to go on-chain, and it's more like a tributary within macro liquidity.
Anyway, I personally prefer to look at exchange inflows and outflows along with overall risk appetite, rather than taking correlation as causation.
By the way, the recent buzz about NFT royalties is really about liquidity and the tug-of-war over whether "creators should be continuously rewarded," which is the same as whether funds are willing to move in the secondary market...
That's all for now.