Find: why the regex with egrep doesn't work?

Question

The first example without pipe return empty.

find /tmp/txz/httperf/httperf-20210403git/ -regextype posix-egrep -regex [A-Z][A-Z]$

The second return what I want, all files with capitalized letters, why the find command return nothing?

find /tmp/txz/httperf/httperf-20210403git/ |egrep [A-Z][A-Z]$ 
/tmp/txz/httperf/httperf-20210403git/.git/refs/remotes/origin/HEAD
/tmp/txz/httperf/httperf-20210403git/.git/logs/refs/remotes/origin/HEAD
/tmp/txz/httperf/httperf-20210403git/.git/logs/HEAD
/tmp/txz/httperf/httperf-20210403git/.git/HEAD
/tmp/txz/httperf/httperf-20210403git/NEWS
/tmp/txz/httperf/httperf-20210403git/COPYRIGHT
/tmp/txz/httperf/httperf-20210403git/AUTHORS
/tmp/txz/httperf/httperf-20210403git/TODO
/tmp/txz/httperf/httperf-20210403git/src/lib/README

I have tried also posix-extended and posix-basic for regex-type, but return empty.

Answer 1

As POSIX find does not specify -regex, I assume GNU find.

Test: -regex expr
Test: -iregex expr
True if the entire file name matches regular expression expr. This is a match on the whole path, not a search. […]

^{(source, emphasis mine)}

You should use -regex '.*[A-Z][A-Z]'. Note the expression is single-quoted to prevent expansion by the shell.