Day 1 Day 7 change (one 24-hr peak per day).
High Low (biggest % drop)

S15 −44.1% (−26,163)
S16 −36.7% (−22,047)
S6 −33.1% (−25,018)
S17 −27.3% (−10,199)
S18 −20.5% (−12,074)
S8 −20.0% (−7,784)
S7 −18.1% (−6,939)
S13 −14.7% (−8,570)
S11 −14.1% (−7,104)
S10 −14.0% (−8,534)
S12 −14.0% (−8,283)
S9 −9.2% (−3,841)
S14 −3.3% (−1,335)

Season 18, the era of generous lootboxes, 77 for you and I! Was THIS the season that restored the games honor? Was the Forbes article correct in saying that Overwatch is back baby and the rivals is kill? Sadly not. It has been more of the same, and the downward trend continues despite the large initial influx of players.

S18 Day-1 Day-7: 58,795 46,721 (≈ 79% retained, −21% drop) | 5th-largest drop of all seasons measured — better than S15/S16/S6/S17, but worse than most others (S10/S11/S12/S13/S7/S8/S9/S14).

People are coming back to the game, they're just not sticking around. I don't know the reason why, but it seems that loot boxes weren't enough. The downward trend continues, though not as severe as the previous seasons, but still quite awful.