ETF approval is an obvious sell the news event. I believe there's a large rotation in place from GBTC to competitively priced ETFs happening, which doesn't explain the whole decrease but would have a volume impact on price especially if Blackrock, Franklin Templeton etc had already purchased/seeded their bitcoin for their ETFs.
This selling should be temporary, basically until Grayscale run out of Bitcoin to sell, or decide to reduce their ETF fee to something competitive the selling will continue until one of those is true.
Halving is in April and typically within a couple of months the supply shock will hit and we'll be off to the races.
