Optimism Mainnet has initiated a four-week experiment introducing stake-based transaction prioritization, marking its first adjustment to transaction ordering rules. Traditionally, the sequencer prioritized transactions by the highest gas fee, but now users can opt into a new system by staking at least 100,000 OP in the PolicyEngineStaking contract. This trial, approved by Optimism's governance, will run until June 23. The experiment is divided into two phases. In Phase 1, lasting one week, a FIFO (first-in, first-out) system is used, where staking above the minimum does not influence priority. Phase 2, spanning the remaining three weeks, implements a weighted priority gas multiplier based on staking duration, enhancing priority for longer stakes. Non-participating users will continue under the existing priority gas auction (PGA) mechanism.