The developer downloads page now lists an Xcode 26.1 which was released on 11th Dec (the original Xcode 26.1 was posted on 3rd Nov).
Strangely, this new Xcode 26.1 has a CFBundleShortVersionString of 26.1.1, and a DTXcodeBuild of 17B55
% ls -ln
total 4413136
-rw-r--r--@ 1 503 20 2259523057 16 Dec 19:01 Xcode_26.1_Apple_silicon.xip
% xip --expand Xcode_26.1_Apple_silicon.xip
xip: signing certificate was "Software Update" (validation not attempted)
xip: expanded items from "/Users/me/Downloads/temp/Xcode_26.1_Apple_silicon.xip"
% plutil -p Xcode.app/Contents/Info.plist | grep CFBundleShort
"CFBundleShortVersionString" => "26.1.1"
% plutil -p Xcode.app/Contents/Info.plist | grep DTXcodeBuild
"DTXcodeBuild" => "17B55"
17B55 does correspond to the original Xcode 26.1 final release. The Xcode 26.1.1 release that was previously posted had a DTXcodeBuild of 17B100, though. The pairing of 26.1.1 and 17B55 looks new and probably a packaging error?