One of the largest upgrades in recent years — Fusaka — has been deployed on the Ethereum network. The BeInCrypto editorial team has gathered the initial consequences of the event in one material.
We explain how Fusaka changed Ethereum and what is happening with the price of ETH against the backdrop of the upgrade.
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What is Fusaka and why was the upgrade necessary
The Fusaka upgrade was activated on December 3, 2025, and became the next major step in the development of the protocol after Pectra. It combines two components from different layers of the network: Osaka, responsible for executing transactions and running smart contracts, and Fulu, which manages validators and block creation. After a long period of separate development, these elements began to work in a unified architecture, forming the basis for scaling Ethereum in the coming years.
One of the key innovations was the PeerDAS mechanism. It changes the way blob data is processed — large temporary sets of information published by L2 networks. Before Fusaka, each node had to download the entire volume of such data. Now the blob is broken into fragments, distributed among network nodes, and validated selectively. This approach reduces the load on the nodes and allows L2 to publish significantly larger volumes of data without risking infrastructure overload.
The value of PeerDAS was commented on by Vitalik Buterin. According to him, this mechanism represents the first working form of sharding. Sharding is the division of data and load among network participants so that no single node is required to store or process the entire array. Ethereum has been moving towards this idea since 2015, and data availability proofs have been discussed since 2017. Now the technologies that have been talked about for almost a decade are working in the mainnet.
Below is a schematic representation of the mechanism, which Buterin accompanied with a post:
Buterin noted that the system is still incomplete. The throughput of L2 is growing faster than that of L1. Block assembly still requires a full dataset, and there is no sharded mempool. Fusaka creates a foundation on which developers will gradually scale PeerDAS, test its resilience, and prepare for the moment when mature ZK-EVMs will allow scaling L1 itself.
Along with PeerDAS, other changes came to the network. Small BPO forks allow for flexible increases in the available blob space without major hard forks. Optimization of MODEXP, new gas limits, block size restrictions, and an increase in gas limit to 60M make the network more stable. User tools have also been updated: native support for secp256r1, opcode CLZ, and a predictable mechanism for determining future block producers have been introduced. The network has become faster, more reliable, and less resource-intensive for nodes.
The first consequences of the Fusaka upgrade
Immediately after the activation of Fusaka, effects began to manifest that indicate the high sensitivity of the ecosystem to changes in data processing. A number of network metrics shifted literally in the first hours.
The increase in the cost of publishing blob data
The cost of publishing blob data increased almost instantly. Before the upgrade, publication cost 1 wei, and after the activation of Fusaka it rose to about 1500 wei. Such payments are called blob fees — this is the price for offloading large datasets that L2 sends to Ethereum to record their activity. The sharp increase is explained by the fact that enhanced publishing capabilities immediately led to an increase in data volume: L2 began to upload more information to the network than before, which instantly changed the level of demand.
According to Flipside Crypto, the volume of ETH burned increased by 39% after the upgrade activation. The average transaction fee rose by approximately 46%. Despite the increase in costs, user activity remained at the same level.
Such a combination — rising fees, accelerated reduction in supply, and a stable flow of transactions — creates a noticeable supply shock. Against this backdrop, some analysts allow for a price movement towards $4,650 if the current dynamics persist.
In one day, according to CoinMarketCap, Ethereum increased in price by 4%. More forecasts for ETH in light of Fusaka are in our review.
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