What do you mean by qBittorrent data?
If you do Windows upgrade then almost everything you currently have should be kept as is and you have maybe 10 days to revert and go back to previous Windows if didn't do big changes to Windows.old folder.
If you do upgrade and selected not to keep settings, files and programs, then after installing Windows 11, your main C drive should have Windows.old folder that has everything you had on previous Windows install and you manually need to move your important files and program settings and database files before reinstalling your programs, or make a backup of important folders and try to move things to correct place later on before your Windows.old gets deleted automatically.
Now if upgrading took too long or noticed weird issues then better to try clean installation, shouldn't take longer than 20min even if got HDD, just need to run setup using USB during bootup and select to delete all partitions, doing so many previously experienced anomalies should not reappear.
Newest stable Win11 22H2 has file copying speed issue for some users, so maybe better to try Win11 21H2 or wait for it to get fixed in Win11 22H2.
Now if curious to know where does qBittorrent save it's settings and transfer list, then it's written in qBittorrent Wiki FAQ (Frequently Asked Questions) page:
https://github.com/qbittorrent/qBittorr ... s-settings
If you can't see APPdata folder, then open Windows File Explorer settings and enable showing hidden files and folders.
After installing newer Windows, recheck your qBittorrent Advanced Settings if you need to bind Network Interface and to specify new IP, if you don't use VPN and never modified these settings then no real need to look at them, although specifying these 2 could maybe help to sometimes get lower resource usage on some hardware and OS configurations.
Now if you wish to transfer downloaded torrents, then you can use qBittorrent to specify new download or save locations.
In future better to ask help in GitHub, there is higher chance to get help quicker and in discussions page you can afterwards mark your question as answered.
https://github.com/qbittorrent/qBittorrent/discussions