This continue to be pretty normal - this rc is slightly larger than rc4 was, but that looks like one of the normal fluctuations due to timing of pull requests, not due to anything distressing. In particular, this past week we had both a networking pull and a drm pull, which accounts for a fait chunk of it all.
In addition to the networking updates (both drivers and core networking) and the drm stuff (mainly some amdgpu display handling updates), there's the usual arch fixes (mostly x86 this time - microcode handling and some syscall cleanups) and various random driver fixes (rdma, md, scsi, watchdog). Plus some misc stuff: filesystems (overlayfs, xfs) some core kernel code, and tooling (mainly perf and selftests).
Nothing particular stands out, the appended shortlog gives a flavor of the details.