When I run your above example, Perl tells me various things that are wrong with it:

> perl -w 1.pl
Unquoted string "colored" may clash with future reserved word at tmp.p
+l line 2.
Name "main::colored" used only once: possible typo at tmp.pl line 2.
print() on unopened filehandle colored at tmp.pl line 2.
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The use Term::ANSIColor; statement happens too late for colored to be interpreted as a function. If you use (for example) parentheses, your intention is clear to Perl:

print colored(['red'], "test");
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Have you read the documentation for use and require? That documentation explains the difference you observe in your update.

You may want to read perlmod about BEGIN, UNITCHECK, CHECK, INIT and END to find out what phases run when.

"However "require '2.pl'" is before "colored" statement."

2.pl is loaded before the colored statement is executed, but not before it's compiled. Therefore the Perl compiler doesn't know that colored is a function; it thinks it's a bareword filehandle.

Is that bug and how to fix it?

If you look up the docs for use and require you can answer that question in about one minute if you're a slow reader