Fusaka upgrade faces a harsh reality check: Ethereum's high Blob failure rate exposes scaling bottlenecks

After Ethereum completed the Fusaka upgrade in December 2025, it was expected to enter a new phase of scalability. However, the latest data has dealt a cold shower. According to analysis by blockchain research firm MigaLabs, the upgraded Ethereum performs poorly when processing data-intensive blocks, raising questions about whether it can truly support larger-scale Layer 2 throughput.

The Gap Between Expectations and Reality of the Fusaka Upgrade

The core goal of the Fusaka hard fork is clear: to allow Layer 2 networks to submit more blob data to the Ethereum mainnet, thereby reducing Rollup costs and increasing scalability. It sounds promising in theory, but actual operation has not fully met expectations.

Capacity Expansion Not Fully Utilized

Based on data from over 750,000 block slots since October 2025, MigaLabs found an awkward phenomenon: although the official target number of blobs per block has gradually increased to 14, the median number of blobs in actual blocks has decreased. Even more surprisingly, blocks containing 16 or more blobs are extremely rare, occurring only a few hundred times during the entire observation period.

What does this indicate? The expanded capacity is far from fully utilized. The upgraded network capacity is like a wide, newly paved road, but traffic flow has actually decreased.

Rising Failure Rates: A Real Hidden Danger

More concerning is that as the number of blobs increases, the probability of blocks being missed by the network rises significantly. This is the core issue.

The implications behind the data are clear: once the block data volume reaches a certain threshold, the network’s processing capacity begins to experience noticeable stress, and the failure rate skyrockets. This is not just a performance issue but also a stability concern.

Direct Impact on Layer 2

These high-data-volume blocks mainly come from large Layer 2 networks like Arbitrum and Base, which heavily rely on Ethereum’s data availability to maintain their security. If these blocks are missed by the network, it means Layer 2 transaction data is not confirmed by Ethereum in time, posing a potential threat to the stability of the entire ecosystem.

The Dilemma Moving Forward

If Layer 2 activity continues to heat up in the future, with more frequent high-blob blocks, this compounded failure rate could put pressure on Ethereum’s overall stability. MigaLabs recommends delaying further increases in blob capacity until the failure rate in high-data blocks drops back to the benchmark level and actual demand approaches the current upper limit.

This essentially reflects a fundamental trade-off Ethereum faces:

• Continue scaling: may exacerbate instability
• Hold back on scaling: may constrain Layer 2 development potential

Meanwhile, the Ethereum Foundation is also planning for long-term security. Researcher Justin Drake has announced the launch of a post-quantum cryptography initiative, led by Thomas Coratger and Emile, with a $2 million investment. This indicates that Ethereum is facing more refined technical trade-offs between scalability and security.

Summary

The issues exposed by the Fusaka upgrade deserve attention. On one hand, the capacity expansion has not brought the expected increase in activity; on the other hand, when data volume truly rises, the network’s failure rate increases sharply. This is not merely a performance problem but a technical bottleneck affecting the stability of the entire Ethereum ecosystem.

For the Layer 2 ecosystem, this means that short-term expectations of significant cost reductions should be tempered. For Ethereum itself, a better balance must be struck between scalability ambitions and system stability. How this problem will be addressed in the coming months may be more important than price fluctuations.