I don't know if there are many/any folks visiting Paris today, but in addition to severe restrictions with public transport, you also have to deal with the related protest march, which today will be all on the Left Bank.
Marchers will gather at Sèvres -Babylone and depart around 2 pm headed for Place d'Italie. Press reporting projects around 60,000 to 90,000 people could participate.
I would suggest avoiding that entire area this afternoon !