I found this: https://discuss.privacyguides.net/t/sam-bent-tor-browser-s-latest-update-could-get-you-fingerprinted/26973/6

Basically if you are asking whether the decision is intended to affect privacy somehow, it isn't. Really the deal is that TCP/IP connections look slightly different from eachother depending purely on the operating system sending the data, so even with spoofed OS information in HTTP headers and even with Javascript disabled attackers can still passively identify the operating system. The Tor Project weakened their HTTP OS spoofing to fix some inconvenient behavior, but it's still nothing that couldn't be determined anyway.