This announcement caused panic throughout the crypto space. A lot of people resorted to selling their bags to buy more at a lower price. This resulted in a red market throughout the day.
The markets did dip yesterday on the news, but to be honest the Stock Market makes no sense these days.
An important thing to consider is that there are different tax implications between Stocks (Securities) and Cryptocurrencies (Property). In crypto it makes sense to sell some coins, lock in a lower capital gains rate, and then buy right back in. That advantage isn't there for stocks. There are wash sale rules and plenty of other little profit calculation rules that apply to stocks.
Journalists always seem to write these articles where they try to explain a broad market move with a specific piece of news.
In general I think they are mistaken. The market moves on its own. Had the annoucement of capital gains market happened 2 months ago when there was really strong upward momentum in crypto, then I think it would have been completely ignored.