Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
22.5 airbnb 's failure to enforce any right or provision in these terms will not constitute a waiver of such right or provision unless acknowledged and agreed to by us in writing . 

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. OPTIONS: ["Unilateral change", "Limitation of liability", "Arbitration", "Jurisdiction", "None", "Content removal", "Choice of law", "Unilateral termination", "Contract by using"].