How to list exchange studies in CV?
It seems simple enough to be clear as your double bullets aren't, implying two degrees. 


  Bachelors Degree: ETHZ, 2021 (with studies at ETHZ (2017 - 2020) with thesis work at RITS (2020 - 2021) as a visitor 


It is clear when the single degree was given, and by which university as well as some indication that some study was undertaken at RITS. 

Other variations work, of course.