There are no photos provided so I will be just making an assumption. I presume the fillers were injected in your undereye area to improve your tear trough. The possible reason for this is what is called the Tyndall effect. This is due to hyaluronic acid fillers being injected too superficially into the skin and or in too large quantities. This results in a bluish discolouration due to the light reflecting off the filler particles with increased scattering of the light. Thus, the area treated looks darker due to the discolouration. Hope this helps!

Migration of filler is defined as the presence of filler at a location remote to the primary area of injection. A brief literature review brings up a single case study that was published in 2016. In summary, A 33 year old lady presented with 2 lumps on her forehead 16 weeks after filler injection to her nose bridge and it was concluded to be due to filler migration. (1) Nose augmentation with filler involves deep placement of filler to augment the nasal bridge ( in between the eyes), along the dorsum of the nose to the tip and including the columella .