Why a process can own 3 names in Linux?

We migrated an app, changed its name in Makefile from flex_camera to flex_camera_lucid. After deploying it to the target board(the original app is removed), as shown in the following screenshot, we get 3 different names of one process! But why? For the original app flex_camera, we can find it by ps -e or pgrep. But for the migrated app, neither ps -e | grep flex_camera_lucid nor pgrep flex_camera_lucid works. So, why? Finally,what are the determinations of the name of a process in Linux ? --- Makefile:

TARGETS = flex_camera_lucid

#...

.PHONY: default
default: $(TARGETS)

$(TARGETS): $(OBJS)
	$(LD) $(LDFLAGS) -o $@ $^ $(LDLIBS)

Linux console screenshot: