It's just one of the idiosyncracies of the .win network.
If you come here through KiA2's own URL, https://kotakuinaction2.win/, and you click a user profile to check a user's posts, you only see posts on KiA2. If you use https://communities.win/c/KotakuInAction2/ and do the same, you see the user's post history on all communities. I'm guessing /uBidenLikesMiners uses the former, so he thought you only two posts total.
It's just one of the idiosyncracies of the .win network.
If you come here through KiA2's own URL, https://kotakuinaction2.win/, and you click a user profile to check a user's posts, you only see posts on KiA2. If you use https://communities.win/c/KotakuInAction2/ and do the same, you see the user's post history on all communities. I'm guessing /uBidenLikesMiners uses the former, so he thought you only two posts total.