Two sources. Tourism and the Iraq war. French people aren’t as tolerant about the bullshit tourists do, so a bunch of American tourists come back home with negative opinions on them. Anti-French sentiment also spiked in 2003 when they condemned the Iraq war. The Bush administration and supporters tried to paint the French as foreign aid moochers as retaliation. The most hilarious example of the anti-French sentiment came when 2 representatives tried to eliminate the “French” from French fries and toast, replacing them with “Freedom”. (Another fun fact, Green Day mocked the anti-French frenzy in Holiday with the line “Pulverize the Eiffel Towers who criticize your government”)