GS and other sell side firms make upgrade and downgrades all the time, GS might downgrade, but other firms might upgrade
not everyone, except the usual clueless idiots, watch only and exclusively at GS to see where the market is heading
as long as GS can reasonably justify the downgrades based on facts and analysis, and the right disclosure, they are allowed to do so.
But if they were on Twitter and YT doing the same, without disclosure or proper explanation, then yes, they would be in violations.