You can follow these steps to achieve effect.
#1. First, find Gallery ID
In my example, it is:
section[data-section-id="66aba2c59905c849edbe7322"]
#2. Use this code to Custom CSS box. Replace Pixabay with your image url.
section[data-section-id="66aba2c59905c849edbe7322"] { figure:nth-child(1):hover img { content: url(https://cdn.pixabay.com/photo/2023/04/07/05/59/woman-7905583_1280.jpg); } figure:nth-child(2):hover img { content: url(https://cdn.pixabay.com/photo/2024/01/25/10/50/mosque-8531576_1280.jpg); } figure:nth-child(3):hover img { content: url(https://cdn.pixabay.com/photo/2024/02/23/19/37/tufted-duck-8592681_1280.jpg); } figure:nth-child(4):hover img { content: url(https://cdn.pixabay.com/photo/2024/08/02/21/54/antique-car-8940770_1280.jpg); }}
#3. Note