Unless passed the -I option, fdfind ignores the same files git ignores and more by looking into the same files as git looks into plus a few of its own.
Quoting the description of the -I option from its man page on Debian:
-I, --no-ignore
Show search results from files and directories that would otherwise be ignored by
.gitignore
.git/info/exclude
- The global
gitignore configuration (by default $HOME/.config/git/ignore)
.ignore
.fdignore
- The global
fd ignore file (usually $HOME/.config/fd/ignore)
The flag can be overridden with '--ignore'.
To see which of those conf files (and possibly more) fdfind finds, you can run it as:
strace -ze file fdfind test
Where strace will report the successful (-z) file-related system calls fdfind makes where you might see it open a .gitignore file in the parent directory or parent's parent or some other file that specifies patterns of files or directories to ignore in a gitignore fashion.