You might remember, but the movie that went head-to-head with Chainsaw Man: Reze Arc was

It was Director Park Chan-wook's "I Can't Help It"
The lead actors went on variety shows like "Pinggyego" to promote it
SBS even produced a documentary-style variety show about Park Chan-wook
They put a lot of effort into promotion
Personally, I enjoyed watching it
And Director Park was clearly aiming for a box office hit
But it got taken down by Chainsaw Man: Reze Arc,
which probably didn't care at all
3.45 million vs 2.94 million
A difference of over 500,000.