I purchased sketchup pro in 2015, and have happily used it well since. I'm extremely upset over the fact now I can't convert 2017 content (using Sketchup Make 2017) down to 2015 for use. This is almost like a forced situation to force me to cough up money for something I don't really need (like sketchup 2021).
Am hoping someone writes a convertor out there to be able to convert 2021 files down to 2015. Infuriating to say the least!