[BUG] Fix inconsistency in fixed cost vs. lane limit application

This is an issue created on the back of L1 Daily on 14th March '25.

The objective of this issue is to fix the gas limit logic. The team identified inconsistency in fixed cost vs. lane limit application.

Issue detail:
- Fixed cost should be based on lane definitions but currently uses system costs, leading to discrepancies.
- Some transactions cost more than expected due to mismatches between configured lane limits and applied costs.

Start by tracing the gas limit logic and comparing how fixed costs are derived from lane definitions versus system costs. Confirm the configured lane limits and applied costs for affected transactions, then verify that fixed costs consistently follow the lane definitions.

Written by the indexing model from the issue text.