We can specify the biggest challenges in Microservice deployment in two ways, i.e., technical and functional.

The main challenges from the business point of view:

Microservices require a heavy investment.

It requires a heavy infrastructure setup also.

We need excessive planning for managing operations overhead.

It cost a lot in staff selection and maintenance.

The main challenges from a technical point of view:

The components in microservices always rely on each other, so; it requires communication between them in the application.

There are also a lot of challenges in deployment.

Testing and Debugging are very challenging.

It requires complete component automation and application maintenance.

It receives heavy operations overhead.

It requires skilled professionals to support heterogeneously distributed microservices.

https://www.spiceworks.com/tech/data-management/articles/top-10-challenges-of-using-microservices-for-managing-distributed-systems/