In my experience after the price halves to scare investors (will be a bear trap) then after 2/3 months the market starts going up (halving bull run), which lasts 9 months or 10 months.
It seems you are talking about the price here OP and you are really precise that we will talk about the exact day of the Bitcoin block halving, as even in previous Bitcoin halvings of Bitcoin, nothing really important events or dumps/pumps during the exact day of Bitcoin block halving so for me, it's kinda a normal day.
Only the RUNE on the Bitcoin network shocked me because of the transaction fee they used.