Description:
------------
Initially reproduced on Arch Linux and Windows Server 2016:

php -v
PHP 7.4.0 (cli) (built: Nov 30 2019 10:43:49) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.0, Copyright (c), by Zend Technologies
    with Xdebug v2.8.0, Copyright (c) 2002-2019, by Derick Rethans

php.exe -v
PHP 7.4.0 (cli) (built: Nov 27 2019 10:13:59) ( NTS Visual C++ 2017 x64 )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
    with Zend OPcache v7.4.0, Copyright (c), by Zend Technologies



As 3v4l shows, this behavior is exclusive to PHP 7.4: https://3v4l.org/rEqh2

Test script:
---------------
<?php
abstract class Foo
{
    abstract public function Bar();
}

$ref = new ReflectionClass(Foo::class);
var_dump(Reflection::getModifierNames($ref->getModifiers()));

Expected result:
----------------
Calling getModifiers on a non-static class does not detect it as static

Actual result:
--------------
Calling getModifiers on a non-static class detects it as static