You can backup your datadir to an external drive so that when you reinstall Windows 10, you can simply reinstall the Bitcoin Core program and copy the datadir back to your internal drive.
Since your node is pruned, it should even fit inside a USB stick, so I don't think you will have to go out and buy any additional hardware.
How did Windows 11 decrease the lifespan of your SSD though? I am confused about that.
Well, should I just backup the data directory? I have 2 directories here, one is the Bitcoin core directory and the other is the data (I think the nodes are downloaded there) directory.
What I want to add is that in mid-October Win10 will go out of support and then you may want to upgrade again. Plus, I would give more attention/research on what could have caused your SSD issues and your lag, just blaming it on Win11 makes no sense to me. So you may want to reconsider this "going back to Win10". I am telling this because I find your "solution" a wasted effort: I expect you'll go to Win11 soon.
Of course, it was just an advice; you do as you think it fits, it's your hardware and your time.
Actually, I saw many posts on Facebook about SSD corruption. Many people say that their PCs have turned off while playing games. Also many people say their ssd crashed even, while PCs shutdown. So from there, I assumed that this is a problem with the Windows 11 update. Actually, this problem mainly occurs when transferring files over 50 GB. Since I downloaded the Bitcoin core, which is about 600 GB, this may be the reason for the problem. So I am planning to go back to Windows 10.
I bought a new notebook with Windows 11 installed. I tried it for two days, and got rid of it. I installed Ubuntu on the drive, and it is much faster and easier to use for my purposes. Copilot and cloud storage, together with all the spyware and vulnerabilities make Microsoft products a non-starter for me.
Yes, I am also thinking of switching to Linux, I have also tried Linux Mint before, but the problem is that I do not like using Linux because I have been a Windows user for a long time. And there is no such support for games in Linux, and there are also problems with Adobe products. But i know Linux is open source and best for security .So I am thinking of switching to Windows 10 for a few days.