What effect is BTC halfening *supposed* to have?

Other than reduction in BTC rewards won by miners, what other effects is halving (halfing/halvening/halfening?) supposed to have?

I guess this is a technical/cryptocurrency question as well as a financial market question.

I've simultaneously read people say (common discussions on the bitcointalk forum) halving is coming up, so price is going to increase; and also halving is coming up, so price is going to decrease.

Many folks and sites are counting down the upcoming halving (20 April 2024) as a positive event to look forward to. Why? Was there a clear correlation of price and halving in the past?