According to Odaily, Fractal Bitcoin has responded to user feedback regarding incomplete block filling on its mainnet. The company stated on the X platform that they have initiated an investigation into the matter. The issue arises because miners prioritize high-fee transactions and are constrained by two block size limits: the maximum block size in bytes and the maximum number of SIG operations.

When faced with a large number of high-fee MULTISIG transactions, a block can reach the 80,000 SIG limit, preventing the inclusion of additional transactions. Typically, SegWit transactions consume 1 SIG, theoretically allowing up to 80,000 transactions per block. However, this limit is rarely observed in practice. MULTISIG transactions consume 84 SIGs, meaning if a block is filled entirely with such transactions, the maximum number of transactions per block reduces to 952. This results in blocks not being fully filled in terms of bytes.

Fractal Bitcoin noted that some random blocks are completely filled because they include low-fee, non-MULTISIG transactions, occupying the remaining 75% of block space and increasing total block fees by approximately 20%. The company clarified that this situation is due to the existing mechanisms of the BTC mainnet and not a flaw in the Fractal browser. They assured users that they will continue to monitor the situation closely and work on improving network connectivity and performance.