git and filemodes

[Jim Garrison]

Win 10 20H2 with latest Cygwin

$ cygcheck -c cygwin git
Cygwin Package Information
Package              Version        Status
cygwin               3.3.3-1        OK
git                  2.34.1-1       OK


$ git diff .gitignore
warning: LF will be replaced by CRLF in .gitignore.
The file will have its original line endings in your working directory
diff --git a/.gitignore b/.gitignore
old mode 100644
new mode 100755

But

$ ls -l .gitignore
-rwxrwx---+ 1 Administrators None 84 Dec 15 16:30 .gitignore

So it appears the actual file is mode 0770, not 0755 as git is claiming.

Am I misinterpreting something here?
If not, why does git think the mode is 0755?