Both org.lwjgl.opengl.GL45 and org.lwjgl.opengl.GL45C in lwjgl3 have methods void glGetnUniformfv(int program, int location, FloatBuffer params) and float glGetnUniformf(int program, int location) and associated forms for double, int, and unsigned integers.

However, for both the integer forms glGetnUniformiv/glGetnUniformi and glGetnUniformuiv/glGetnUniformui these methods either consume FloatBuffer as the final argument, or return float in the case of the non-v methods.

This appears in (as of writing, the selected tree/blob was also the master branch)
https://github.com/LWJGL/lwjgl3/blob/ef642957c10d9b6f03774c49faa1d09937996553/modules/lwjgl/opengl/src/templates/kotlin/opengl/templates/GL45Core.kt
at the end of the file, primarily lines 1419 for glGetnUniformiv and 1428 for glGetUniformuiv

As a note, by going through the commit history of the GL45/GL45Core.kt files, this issue has been here since OpenGL 4.5 was originally supported by lwjgl3 in https://github.com/LWJGL/lwjgl3/commit/57c2db0855379b6fe76a64fce9752586e4b62d05

Thank you, will be fixed in the next snapshot with 7cf5f4f.