@ bxrlover... I checked my notes to be certain that my details above on May Day 2018 in Paris were accurate. The violence on May Day then took place near or at Gare d' Austerlitz. I was at Nord, which is the stop for the RER from Paris CDG. On the EuroStar I got to Nord before the official check-in time but, no problem, checked in anyway, started watching the French news later.
The violence and property damage caused by Black Bloc was all over the French news, obviously, some channels went into more detail.
My hotel is a minute or two from the station, so I don't need to rely on the Metro or taxi (have done that very rare option too ) from Gare du Nord to reach the hotel, deal with traffic jams, or whatever.
As I pointed out, if I had not turned on the TV to watch the French news channels and follow this "stuff," I would not have known any of this happening since I would not have gone out to the Gare d' Austerlitz area.
Nothing was out of the ordinary at Nord or Gare de l'Est, eg, no extra police presence, etc. or elsewhere in Paris for the next few days.
You can tell if it is "normal" or not, whether something is amiss, so to speak.