After the halving, many ASIC models will either become unprofitable or give very little profit. And in order for large companies to use all the power for maximum profit, they will turn off thousands of old ASIC models.
And what will happen to these ASICs next?
Will they be sold to other countries or disposed of?
If you want to buy a used ASIC now, don't do it. After halving there will be a big discount on such ASICs on the market.
Once halving cuts profits, many mining firms will sell or scrap older ASICs. Expect big discounts but also consider energy costs before buying. A cheap miner isn't always profitable.