announcing the US is going to be invested in propping it up

It’s kind of the opposite though:

The reserve will be funded by coins that have been seized in criminal and civil forfeiture cases and there are no plans for the U.S. government to buy more bitcoin. After the strategic reserve announcement last Thursday, crypto prices declined as investors were disappointed it wasn’t a more aggressive program.

When they announced it at first people expected it was going to be a transfer of wealth from US taxpayers or debt to Bitcoin holders, but it turns out they aren’t doing that after all, so price corrected downwards.