James Seyffart, Bloomberg ETF analyst, attributed the SEC’s pause on Grayscale’s GDLC ETF conversion to the lack of an established legal framework for altcoin-based ETFs

Quotes that support claims

The SEC doesn't want to let anything to launch under the 19b-4 process until they officially approve or come up with some framework for digital assets in the ETF wrapper.

Bloomberg analyst James Seyffart hypothesized that the SEC doesn’t want to launch any altcoin ETFs without establishing a new legal framework.