Why does the scala compiler eliminate runtime visible local variable annotation during compilation?

I found annotations on local variable were not passed to bytecodes after compilation.
And it seems like the compiler code removes any runtime visible annotations on local variables intentionally.
Is there any reason for this?

Thank you in advance.

Could you provide more details - like the scala version and some code showing the issue? Scala compiler does try to preserve annotations but there are occasional issues - I have seen 1 or 2 on scala 3 compiler - eg https://github.com/lampepfl/dotty/issues/12492

Firstly, I made my own java annotation with element type = local variable and retention policy = runtime.
Applying this with java source code, I could find this annotation in the bytecode after java compilation with ‘javap’.
I did the same with scala source code and scala compiler and found the annotation is gone, tried with both scala 2(2.13) and 3.
After that, found the assertion code in scala compiler, which asserts when local variable annotation is remained after some compiler job. (LocalOpt.scala, line 405)
It seems that annotations on other kind of symbols works fine but not on local variables.