This is the commit:
https://github.com/btc1/bitcoin/commit/28ebbdb1f4ab632a1500b2c412a157839608fed0

If segx2 team did that, then other altcoins can also do it ?

jgarzik replied 9 days ago • edited
This is a privacy feature. See discussion at PR #109 for more.

This feature defaults to advertise (privacy=off).

Users may optionally disable advertising (privacy=on).

There is historical precedent with Internet browsers: https://stackoverflow.com/questions/7975996/why-does-internet-explorer-9-report-mozilla-in-useragent

Users also rightly requested privacy features like this due to past attacks:

Bitcoin XT https://news.ycombinator.com/item?id=10140981
Bitcoin Classic https://news.bitcoin.com/bitcoin-classic-targeted-by-ddos-attacks/
Bitcoin Core violated the Robustness Principle as described in RFC 1122 and elsewhere. https://tools.ietf.org/html/rfc1122