[WIP] Remove difficulty from blockchain

[ferranbt]

Description

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Changes include

• [ ] Bugfix (non-breaking change that solves an issue)
• [ ] Hotfix (change that solves an urgent issue, and requires immediate attention)
• [ ] New feature (non-breaking change that adds functionality)
• [ ] Breaking change (change that is not backwards-compatible and/or changes current functionality)

Breaking changes

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Checklist

• [ ] I have assigned this PR to myself
• [ ] I have added at least 1 reviewer
• [ ] I have added the relevant labels
• [ ] I have updated the official documentation
• [ ] I have added sufficient documentation in code

Testing

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• [ ] I have tested this code manually

Manual tests

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Documentation update

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Additional comments

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