The short version is 2 reasons:

• Microsoft requires Windows 11 computers to have special new hardware that not all computers have. Security updates for Windows 10 ends in 3 months. Many people are faced with a choice of buying a new computer, or installing Linux on their current one to save money. Others realize how much Windows 11 sucks shit and switch because Linux is better.
• Gaming on Linux has gotten a lot better recently. For many people, this was the main thing holding them back. Software support in general is better than ever.