diff-filter=R can't identify renaming if not done directly

Hello, quick question about using diff-filter in linux. In the scenario
that in my repository, I first copy file1 to file2, then move file2 to
file3 and delete file1, "git diff" returns

diff --git a/file1 b/file3

similarity index 100%

rename from file 1

rename to file3

  but running "git diff --diff-filter=r" doesn't return anything. Only
flag T will return the change. Can this be considered as a bug?