Hi Indira.
The issue may be related to the water content of the butter. Although Kerrygold is high quality, it has a slightly higher water content compared to some butter specifically made for lamination, which typically has 82% or more fat with lower water content. The higher water content in the butter can cause it to melt and seep through the croissants more easily in the oven.
To prevent this from happening, I would recommend checking that the butter you use has at least 82% fat. Additionally, make sure the dough and butter are well-chilled during the lamination and shaping process. This helps the butter stay firm within the layers of the dough, preventing it from melting and seeping out before the croissant has had a chance to rise and develop its structure in the oven.
Best regards.