The report compares the number of arrests in 2020 -- a year that saw the largest number of huge protests in decades-- to the number of arrests in 2019--which contained nothing approaching the number, scale, or sheer chaos of the George Floyd protests.
This might indicate that journalists are under attack. But it seems more likely that some tiny percentage of journalists at a given protest are arrested at any given protests, and that in years with more protesting, more journalists will be arrested. Crank up the number of events, and you crank up the number of arrests.
In fact, their posted numbers track quite closely with this wiki data on size of protests in a given year [0][1].
2020 - 20,000,000 protesters - 181 arrests
2019 - No protests indicated - 9 arrests
2018 - 3,500,000 protesters - 11 arrests
2017 - 6,600,000 protesters - 38 arrests
The increase in 2020 is out of proportion with the other years, but then the marches in 2017 & 2018 were generic, peaceful protests, while the George Floyd protests where chaotic (as evidenced by the resulting 2 Billion in property damage)[2]
[0]https://en.wikipedia.org/wiki/List_of_protests_in_the_United...
[1]
[2]https://fee.org/articles/george-floyd-riots-caused-record-se...