Arbitrum sequencer is a kind of special node that performs the submission of users’ transactions onto Layer 1 (L1) blockchain technology in a roll-up system. This node is important in the system because it improves scalability, efficiency, instant and soft-confirmation receipts to users.

However, the limitations cannot be underemphasis which are:

1. It operates under its own security assumptions, and cannot utilize security directly from Layer 1 (L1).

2. It may result in latency races or malicious attacks due to Miners or users that want to influence the transaction arrangement.

3. It may result in unresponsive or censoring.

The design of some mechanisms by Arbitrum to mitigate these limitations. These features aim to preserve the trustlessness and censorship resistance of the system. And also allows the sequencer to provide seamless and cheap transactions. The mechanisms are as follows:

1. Delayed inbox

2. Time boost policy

3. Decentralized sequencer model