There are a number of moving components in a Microservice architecture, hence it has more points of failures.
Failures can be caused by a variety of reasons – errors and exceptions in code, release of new code, bad deployments, hardware failures, datacenter failure, poor architecture, lack of unit tests, communication over the unreliable network, dependent services etc.
https://www.bmc.com/blogs/microservices-challenges-when-to-avoid/