I'm assuming for this answer that you and the sellers of the Windows license and the printer are all in germany.
Who purchased what, and when?
- Once upon a time, you purchased a Windows license, directly or with computer hardware. This comes with a right to receive upgrades, and Microsoft makes it increasingly difficult not to upgrade to the latest version.
- Once upon a time, you purchased a printer. With it came either a CD-ROM or floppy disk with the driver, or the license to download it from the web.
The Microsoft documentation almost certainly did not specify that it would work with your printer.
The printer documentation almost certainly specified for which Windows version is was written. If the printer driver does not work with the specified Windows version, you can go the seller of the printer and return it as defective, subject to the usual rules. If the problem came only after a major Windows version upgrade, then you are trying to use the printer in the "wrong" operating system.
If the printer should work with the major Windows version, the question becomes if you have the right to a driver update from the seller or manufacturer of the printer. There was a change in law (§327f BGB, §327a BGB) in this regard in 2022, which requires sellers to provide update for a reasonable time. The law did not try to spell the duration out for various classes of products, and I do not know if there are legal precedents for printers yet. In my personal opinion, a customer would reasonably expect a printer to work for several years, but not decades. Between that range, the lawyers would argue.