That is not a new law. It is Senate bill 3983 that has only been introduced onto the floor. As of June 17th of this year it was read on the floor twice, and has since been sent to committee. This doesn't mean it is going to be a law. In fact if you read the language of the bill, it will likely die in committee given the major corporations whom this would affect, due to just the global revenue numbers delineated in the bill.
Typically a bill of this nature is put forward as political hay. Those constituents that pay attention to what their elected representatives do in Congress will give cudos come election time for the mere effort expended to try to get this bill passed. It won't. The sponsors likely know this. However, they bank on those activists who keep track to credit them for this effort. The think that they thought to take on major corporate social media giants in this way will give them brownie points come election time.
Text of SB3983
https://www.congress.gov/bill/116th-congress/senate-bill/3983/text
Actions:
https://www.congress.gov/bill/116th-congress/senate-bill/3983/all-actions?overview=closed#tabs
2018
Report: 90 Percent of Political Donations from Google Go to Democrats
https://www.breitbart.com/tech/2018...itical-donations-from-google-go-to-democrats/
2017 Ballotpedia
Fact check: Do 97 percent of journalist donations go to Democrats?https://ballotpedia.org/Fact_check/Do_97_percent_of_journalist_donations_go_to_Democrats
Conclusion
During an MSNBC interview on July 14, Rep. Dave Brat claimed the media is biased for giving more attention to the Trump administration's alleged Russian connections than to the issue of Hillary Clinton's connections to foreign money through the Clinton Foundation. Brat said, "Why is that? Well, maybe it's because 97 percent of the donations from mainstream [media] folks go to the Democrat Party."[1]
Brat based his claim on the results of a Center for Public Integrity analysis, which found that more than 96 percent of the donations from journalists to either Clinton or Trump between January 2015 and August 2016 went to Clinton.[4]
Ballotpedia reviewed three other analyses of contributions from donors identified as journalists and found that a majority of the donors or a majority of the donations (depending on the study) benefited Democrats or liberal causes.[6][7][8]
And Twitter has no parent company now but Twitter does own Periscope. The first few links are informative.
https://www.google.com/search?q=periscope political donations
I predict SB 3983 will never get out of committee. Politicians are loath to penalize the hand that feeds them.