Marseille & Nantes are notoriously bad and already have had a terrible reputation well before the 2020s. No offense man, but I don't think you did your research well with this French trip and just picked cities out of convenience. I went to Normandy, Brittany, Grand Est, Paris, and the Loire Valley and experienced the exact opposite of what you experienced. Does France bad areas, yes, but I found the whole French negative stereotypes to be completely overblown.
With Eastern Europe, I was just in Poland and Lithuania and good luck trying to game women there if you aren't Polish or Lithuanian because you will stick out there in akin to being in West Virginia/Appalachian America type of way. Outside the town centers, you see all those Soviet bloc housing and wooden rural shacks. Those Eastern Europeans look rough and look like they would pull out a knife on you if you accidentally stepped on their shoes. I was on a train in Poland and two people stabbed each other over a spot in the train. Those are definitely places where you do not want to disturb the peace especially if you aren't one of them and trying to hit on some insecure guy's woman. If you stay in the touristy areas then you should be fine but be careful if you try and leave those spots because a lot of Eastern Europe isn't accustomed for tourism. Poland is high booty and thinks they are central European and not eastern European which is complete BS. Go outside the fancy tourist areas and it looks more like Moldova and Ukraine than Germany and Czechia.
Now, if I looked Muslim, Indian, or African I would definitely not fvck around in non-touristy parts of Eastern Europe. I can even see White Americans feeling scared there because they are distinguishable from the locals. Again, Tourist areas are completely safe for everyone, but once you start venturing outside it then play with caution. These people have lives too, so as long as you aren't disturbing the peace or being a menace to society then they will be friendly and cordial with you. Just don't be an fvcking idiot and fall for this manosphere/red pill eastern Europe hype because it is all BS lol. They are using escorts and prostitutes because there is no infrastructure for you to game local women there and these are pretty tight knit conservative areas.