@Antoine BIDAULT As per the Support resolution for Cache is in a 'Failed State' for one week
you tried to scale cache but it got failed as cache was stuck in failed state due to its previous scaling operation that got failed due to underlying compute issue on one of the VM. Our PG team worked to recover the underlying computing issue. On 10/6/2023 recovered the cache manually after getting approval from you. Now the cache is in a healthy state and scaling is completed.
I hope this information helps others in the community who are facing similar issues.
Regards
Geetha