Cloud services are on-demand Therefore there is a level of calculated risk in allocating all the resources of a cloud service, because resources are allocated according to statistical projections. In accurate modelling of resources usage common resources allocation algorithms are vulnerable to distortions of fairness or inadequate resource provisioning and inadequate investments in infrastructure.

Risk tolerance is the amount of risk that the leadership and stakeholders of an organization are willing to accept. It varies based on asset and you shouldn't make a blanket risk decision about a particular provider; rather, assessments should align with the value and requirements of the assets Ref: Security Guidance v4.0 Copyright2017, Cloud Security Alliance(used for educational purpose here)

Although very closely related with audits-which are a key mechanism to support assure. and demonstrate compliance-there is more to compliance than audits and more to audits than using them to assure regulatory compliance.
Reference: CSA Security Guidelines V.4 (reproduced here for the educational purpose)

It can lead to loss of governance.
In using cloud infrastructures, the client necessarily cedes control to the cloud service provider(CSP) on several issues which may affect security.
The loss of governance and control could have a potentially severe impact on the organization's strategy and therefore on the capacity to meet its mission and goals. The loss of control and governance could lead to the impossibility of complying with the security requirements, a lack of confidentiality, integrity and availability of data, and a deterioration of performance and quality of service, not to mention the introduction of compliance challenges.
Source: ENISA- Security Risk and Benefits