If it's the same team developing and maintaining all those services, and those services are creating a bigger whole together, then using a single language for a

If it's the same team developing and maintaining all those services, and those services are creating a bigger whole together, then using a single language for all of them will be very beneficial in the long run. Doesn't really matter which language it is. You can easily reuse libraries, observability tooling, don't have to context switch so often, etc. It's not "Which language is best for this project in a vacuum where nothing else exists?". It's "Is this language really so much better suited for this project that it's worth all the additional cost and mental overhead it will introduce?". Not saying it's never the right choice, but it often isn't.