There seems memory leak on sensu-agent.
agent version 5.21.3:
The profile you posted shows a heap that is only 2.5 MB. Is there some other reason you suspect a memory leak?
If you’re comparing the heap to RSS on Linux, that is not a valid thing to do for Go programs compiled with Go 1.12 or higher, as they release memory back to the operating system lazily with MADV_FREE instead of MADV_DONTNEED. See madvise(2) - Linux manual page for details.