Stocks are down because the president of the US has entered a costly trade war, actually.
It's unaffected by tariffs, but its insane valuation is driven by the narrative that Reddit posts can be used to train AI. Without that narrative, you have a semi-toxic collection of forums and the valuation would probably be somewhere in the millions at best, not the current $20 BB.
Amazon is especially vulnerable to tariffs. To be clear, I'm not really staking out a hard position on gen AI being the one true cause here, I just don't find "it's just part of the overall tariff driven market decline" to be very convincing.