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 . 

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