What inspired this question is Prolegomena §18, particularly this passage:
All of our judgments are at ﬁrst mere judgments of perception; they hold only for us, i.e., for our subject, and only afterwards do we give them a new relation, namely to an object, and intend that the judgment should also be valid at all times for us and for everyone else;
So for Kant all it takes for a judgment to be objectively or universally valid is my intention?
I'm also confused with "we" in the text - does that mean we, in the sense of each one of us gives a new relation to the judgment, or we as a collective of humans reaching an agreement?
To name a few examples to make the question more concrete, under this definition of objectivity/universality,
would "the earth is flat" be objectively and universally valid for a sincere flat-earther?
would "I won the lottery today" be objectively and universally valid for someone who intends to win the lottery?
To support the ordinary sense of "subjective" here is the Oxford/Google definition:
based on or influenced by personal feelings, tastes, or opinions.