PUBG Corp appear to have been more transparent with their Korean players as they kept posting the numbers of banned accounts since 16 June 2017. With great cheater numbers come great ban numbers, totaling at over 13 million so far.
With this new info in the open, it seems clear that PUBG Corp are doing weekly ban waves and according to the information posted by a Redditor named sjk045, week 40 was the peak one with just over one million bans in the span of seven days. The exact number is 1.010.163 bans which is quite impressive but it appears to have been in the period when PUBG was at its prime.
There have been 69 ban waves up to this moment and the exact numbers can be found on the official Korean PUBG Cafe's site. Some details might get lost in translation but you can download a PDF file containing the ban info if you feel like doing an accurate mass translation.
The reddit thread offers more statistics, such as the exact number of banned accounts so far, standing at 13.099.548. As the popularity of PUBG dropped, so did the cheaters' interest in the game it seems as the number of banned accounts kept steadily dropping since week 40. The week starting with 24 September 2018 was the first one where fewer than 100.000 accounts have been banned ever since week 25.
Statistics shown offered more insight into PUBG Corp's mentality, pretty much confirming they neglected player base's pleas until it was too late. Week 25 translates into the week starting with 11 December 2017 at which point the hacker infestation was in full swing and yet it turned out to be one of the weeks with sub 100.000 accounts banned.
By the time of week 40, which is the week starting with 26 March 2018, player base was already rapidly declining and the one million bans didn't help retain them. Hackers were a rampant problem in PUBG for months, but the game is also plagued with poor optimisation and bugs.
When PUBG Corp finally decided to act on PUBG's issues, Fortnite was already primed to start breaking records and there was no coming back. PUBG still gets concurrent player peaks of around one million per day but it is clear the game is still shedding players left and right.