Is it common putting tape on injection site after Restylane in tear trough.

I would not say that it is "common," as I have never heard of it.  That does not make it "wrong" or even concerning.  One possible explanation could be that your doctor wanted to put a little bit of compression on the area to reduce swelling, but maybe he or she has another reason.  I would recommend asking your doctor directly what his or her rationale is for the tape.  In general, doctors have very good reasons why they do certain things and we are all different and have our own preferences.  This is not something that should be "concerning" to you and it is likely that it is even beneficial.  It is certainly not harmful, in any event.  If you get the answer from your doctor, please share it - maybe I'll learn something new!  Thanks for your question.

I, personally, have never seen tape placement after doing filler in the tear trough.  That being said, the best person to ask would be the injector as I'm sure they have a good reason for doing it.  They must have given you instructions as well in regards to the tape, so I'm sure that you could call their office and find out what the rationale is for the tape. Best of luck.  I agree with what others have said as far as what could be the possible reason for it...but best find out from the source.