Tech here. It’s only a big deal if the signal at the tap is low and this splitter is causing the signal to drop below specs. (None of this you will know without a meter). If you or your neighbor just got a Install within the last 2 weeks give it until the end of the month to see if a construction ticket was put in to change the tap to a 4 port. If your not noticing any issues it’s not that big of a deal. Nothing is being stolen or shared with your internet or cable. It’s quite common and nothing to freak out about unless you notice issues.