I was just pondering the same question re: do I still need v4 (vs v5). An internet search took me to this thread.
Thought I'd add what I found: Each version has a Logs\ folder. Each Logs\ folder contains ClientLog.txt files. The TurboTax version checking for updates writes to the log.
I still have TT 2018 installed. When I run it, a new v4 ClientLog file is created. If I Stop and Disable the v4 Update Service in Windows and rerun TT2018 it gives an error message telling me it can't update. If I restart the service and restart TT 2018 it runs fine.
No surprise, I see TT 2023 using v5. It'll be a matter running each old version I still have installed to see if they use v4 or v5 update service. I can then decide what I want to do about v4. If TT uninstaller is written well, uninstalling the last TT version still using v4 might even delete the service and clean-up the files as well.!TBD
