This is a yellow( or gold) heart, but Au KDDI and Docomo platforms have designed it as an orange heart. Yellow gives a feeling of calmness and warmth and generally means happiness, loyalty, kindness, honesty and other good qualities.
💛 is often used to represent friendship and happiness, or to show someone is happy and optimistic. Related emojis:
❤💚💙💜🤎🖤🤍❣ Recently, due to the war between Ukraine and Russia, many people on Twitter use 💛 and 💙 to express their support for Ukraine. Because yellow and blue are the two colors on Ukraine's national flag.