Hi @Shan_HBG,
Thanks for reaching out.
The size of an item is based on the amount of content within it, it’s the title and excerpt. The upper 3 items have 2 line title and 5 lines excerpt and they are taller than the 4th item since the 4th has only 1 line title.
Now, the 5th item is smaller than all of 4 items since it has one line title and 4 lines excerpt.
Let’s say you fixed it by changing the amount words in the title and excerpt, or set minimum height, but what if it’s viewed on a smaller device that again, it changes the site as there are long words that could take a single line alone. Hence, even with same word amount and height, it could still change. How about using Essential Grid plugin? Then just use its even layout instead of masonry, please check it here https://theme.co/apex/forum/t/extension-essential-grid/68
Thanks!