TLDR; When Proof of Less Work activates, the difficulty will still increase, but more slowly than before PoLW. For example, at 7 EH/s, the difficulty would be about one-third of PoW difficulty and will eventually converge to one-eighth. The burning rate starts at zero and will converge to seven-eighths at 128 EH/s. For instance, a mining pool or solo miner at 7 EH/s will have to burn three-quarters of their rewards to mine a block.
PoLW is a new consensus mechanism created by @Alephium. It introduces a component that shifts some external costs, like electricity, into an internal component. This internal component aims to reduce energy consumption without sacrificing security. In other words, at the same energy consumption rate, PoLW will be more secure than standard PoW mechanisms like Bitcoin.
In more concrete terms, here is what PoLW means for miners, mining pools, users, and the network:
When PoLW kicks in (at >1 EH/s), solo miners or mining pools will have to burn $ALPH before they can mine blocks. However, miners in a pool don’t have to do anything differently; it will not change their experience. The reward range decreases from 5 $ALPH to 0 overall for all 16 chains (since Alephium is a sharded blockchain). The burn rate is defined by this formula: TOTAL_REWARDS * {(X - 1)/X } * {7/8}, where X > 1 EH/s. This means that as the hashrate increases, the burn rate also increases, starting from 0 and converging to seven-eighths at 128 EH/s. Some people might be afraid of this coin-burning mechanism, but in the long term, the mining emission is more friendly than Bitcoin's (mostly because it starts from 0 with PoLW).
What about the difficulty?
For this part, there will be two new terms, "Real difficulty" and "Virtual difficulty":
Real difficulty or real mining refers to the physical mining hashrate, the one that ASICs produce.
Virtual difficulty is the combination of physical mining plus burning $ALPH.
The real difficulty is the one that is important here. With PoLW, the overall difficulty will increase as the hashrate increases but at a slower pace than it was before PoLW, again starting from 0 and converging to one-eighth of what the hashrate would be before PoLW. It's defined by D_real = 1 + (D_virtual - 1) * (1/8). For miners, this doesn’t change anything; they would have the same hashrate, but with the same hardware, they will provide more security to the network because of the coin-burning component.
At the end, for the network and the users, the goal is to reduce energy consumption for the same amount of security (PoW security + economic security). With @Alephium and PoLW, the goal is not to consume less but to consume better.