Which L2 fees changed post Fusaka?

TLDR

Direct answer: The fees that changed are the Layer 2 data availability blob costs paid to Ethereum (the L1 posting cost per batch). Fusaka added a blob base fee and expanded blob capacity, shifting and lowering L2s DA component over time. See the Ethereum post on PeerDAS, BPOs, and blob base?fee tuning for details here.

1. DA costs: Fusakas PeerDAS and a bounded blob base fee change how L2s pay for posting data, aiming to cut L2 user fees by roughly 4060% over time (overview).
2. Short?term effect: Blob fees initially spiked as pricing normalized, then capacity increases (BPOs) are scheduled to ease costs (tweet).
3. What did not change: L2 execution gas mechanics remain the same; the drop comes from the DA portion of total fees (analysis).

Deep Dive

1. DA Fees Repriced

Fusaka targets the data availability (DA) portion of L2 costs, not L2 execution gas. PeerDAS lets nodes store a fraction of blob data and raises blob capacity, while a new bounded blob base fee stabilizes pricing for L2 batch posts to L1, aligning incentives between L1 and L2s (Ethereum update).

• This rebalancing seeks cheaper, more predictable posting costs and better L1L2 value alignment (Cointelegraph explainer).
• Some coverage projects a meaningful reduction in L2 end?user fees as DA costs fall (Yahoo Finance).

2. Near?Term Volatility Then Relief

At activation, blob pricing normalized upward from near?zero minimums, and some observers noted a sharp initial jump before optimizations and capacity increases kick in (market tweet).

• Scheduled Blob Parameter Only expansions raise blob targets (Dec 9 and Jan 7), adding space for L2 data and easing fees as the rollout completes (ecosystem view).
• OP Stack teams highlighted the path to more blob capacity and lower L2 fees across Superchain networks (Optimism thread).

3. What Did Not Change

Fusaka does not rewrite L2 execution gas rules. The primary lever is the DA charge paid to L1, while L2 gas markets still run their own base?fee logic. As blob space grows and DA costs normalize, the total fee paid by users should fall mainly via the DA component (Cointelegraph explainer).

• The staged capacity increases (BPO1 and BPO2) support the intended fee path without altering L2 execution semantics (ecosystem view).

Conclusion

Post?Fusaka, the meaningful change is to L2 data availability fees paid to Ethereum. PeerDAS plus a bounded blob base fee reshapes and, over time, lowers the DA component, while execution gas on L2s remains the same. After initial normalization bumps, scheduled blob?capacity increases are designed to deliver cheaper, steadier L2 transactions.