Weird sauce. I think it's this motion by Sen. Johnson:
https://www.hsgac.senate.gov/imo/media/doc/Subpoena%20Motion%20-%20Schedule%20A%20(20200528).pdf
The number of people subpoena'd under this motion is 35 (pic), and the motion had been authorized last Thursday in the Senate.
Also, for example: https://www.nbcnews.com/politics/congress/senate-republicans-approve-subpoenas-ex-obama-officials-russia-probe-origins-n1224896