LP gain/loss calculation change -- is it intentional?

Completed my placements, next win gets me ~23 LP, which is normal, since after promos your MMR is higher than your division.

But next day, without me playing games in between, wins started getting me 15-17 LP per win, without any apparent reason. There is nothing in patch notes to indicate a change, so looks like likely a bug to me.

P.S. There are a few similar posts, but Riot might not distinguish those from the regular start-of-season-complaints-about-placement ones, so I'm posting one myself. This is not a general complaint, I'm fine IF formula has changed and now you gain less LP. But signs indicate that this might in fact be a bug, can we have someone from Riot comfirm whether there was an intentional change from how LP gains normally worked at start of season?