There is nothing that explicitly prohibits or opposes the use of stored procedures with microservices.
Disclaimer: I do not like stored procedures from a developer's POV, but this has nothing to do with microservices.
Stored procedures usually work with a monolith database.
I think you are making a logical mistake.
Stored procedures are decreasing nowadays. Most of the stored procedures that are still in use come from an older codebase that still exists. At that time, monolithic databases were much more common than at times when microservices became popular.
Stored procs and monolithic databases both come from old codebases, so you'll see them together more often. But that is not a causal connection. They do not use stored procs there You have a monolithic database. You do not have a monolithic database there They use stored procs.
Most books on microservices recommend one database per microservice.
There is no technical reason why these smaller databases can not have stored procedures.
Like I said, I do not like stored procs. I find it awkward and resistant to future maintenance. I think that distributing sprocs to many small databases further aggravates the problems that I do not already like. That does not mean that it is not possible.
Again, most books on micro-service architecture state that they should be autonomous and loosely coupled. Integrate the microservice closely with this technology using specially stored Oracle stored procedures.
On the other hand, the same argument can be made for the ORM used by your microservice. Not every ORM supports every database. The coupling (especially its tightness) is a relative concept. It's about being as relaxed as possible.
Sprocs generally suffer from tight coupling, regardless of microservices. I would generally advise against Sprocs, but not especially because you use microservices. It's the same argument as before: I do not think sprocs are the right way (in general), but that might just be my bias, and it's not microservices.
Most MSA books (which I read) recommend that microservices should be business oriented (developed with Ddd). Moving business logic to stored procedures in the database no longer works.
That has always been my main problem with Sprocs: business logic in the database. Even if it is not the intention, it somehow always ends like this.
But even here, there is this point of criticism, regardless of whether you use microservices or not. The only reason it looks like that is that microservices are pushing you to modernize your entire architecture and that sprocs are no longer so popular in modern architectures.