The closing of Pennsylvania Avenue has become essentially permanent over the course of the year.  Closures of all of Lafayette Park have increased.  One theory is that they close the park on days when the President’s actions are most likely to spark a protest, however it is difficult to know for sure, given that there are no doubt perfectly normal reasons to close the park to public access (including visiting dignitaries and maintenance or construction activities that require some level of secrecy).  That caveat being noted, the closures are, at least anecdotally, far more common since Trump took office compared to the previous administrations.