Every time I add a comment, the exact same 3 people will "like it". I know that a human is not liking the comment themselves, it must be automatic within the app by the system. Does anybody else get this? Is it a bug with the app?

Yes ? But definitely nothing wromg too. It might be the support group or even those who works in this apps ? or someone who had followed you in the apps or someone who think your questions is good or they are also looking for answers. No worries about that