The sun is positioned in front of each of 12 Zodiac constellations for at least 30 days, completing the complete cycle at 365 days.

That should be the simplest definition of a Zodiac month: Aries when the Sun is aligned with Aries, Taurus when the Sun is aligned with Taurus, Pisces when the Sun is aligned with Pisces.

Tropical astrology does not do this. It starts Aries at the Spring Equinox every year, whether Aries is actually behind the Sun or not.

Tropical astrology is exactly same as True Sidereal / Vedic astrology for the year 285 (AD), but since then, it has been drifting.

In other words, Tropical astrology still uses the names Aries, Taurus, Gemini, and Pisces — but it is not actually based on those constellations anymore. It is a "season-based" (Tropical astrology is what Sidereal astrology once was 1700 years ago, fixed and outdated.) calendar with fixed dates using star names.

True Sidereal / Vedic astrology restores the obvious connection: the Zodiac sign should match the constellation behind the Sun.

5th & 7th uses True Sidereal / Vedic, because your ego is shaped by the constellation behind the Sun when you were born.