Personally, I have experienced that when the area around the Ajna chakra changes from a slightly clouded state to a state of clarity, things become much clearer (easier to observe). In fact, I probably had similar experiences before, but I didn't have a sufficient understanding that the observation was coming from the heart, and I didn't have that feeling. I thought that the Ajna chakra was the one doing the observation.
When entering a state of stillness and engaging in observation (Vipassana), the basic practice of meditation is to focus on the space between the eyebrows. After a while, one enters a state of stillness, but until now, I didn't feel that the observation was coming from the heart. Instead, I suddenly and unexpectedly switched to an observational state, as if a fog were clearing.
However, recently, I have come to understand that the key is the understanding that the observation comes from the heart, and the fusion of the observation of the heart and the concentration of the Ajna chakra.
And then, I suddenly remembered that something similar was written in the works of Swami Yogananda, who founded the Yoga Niketan in Rishikesh, India.

"The Science of the Soul," pages 414-416.
According to the description, the focus is on the Sahasrara (Brahmarandra) being luminous and working in coordination with the Ajna, which might seem to say something different at first glance. However, it also mentions that the Brahmarandra (Sahasrara) and the heart are connected by a band of light, and there is a disclaimer stating that it is impossible to express actual spiritual vision. Therefore, it might just be describing the same thing using different expressions, or it might be saying something slightly different. The true nature of this is difficult to determine from the text alone. At least, this diagram is quite similar to my own experience.
Some people might interpret such descriptions literally and think, "Is this not something completely different?" However, there are many ways to express these concepts, and after experiencing them, when you read the descriptions of others, you often realize, "Ah, isn't this the same thing?" Therefore, it might be a different experience in reality, but at the very least, it can be a clue to deepen your understanding of your own experience.