line gap

i really feel frustated, i dont know how to solve this.

i was read and use it. this arcticle doesnt help
https://www.high-logic.com/font-editor/fontcreator/tutorials/font-metrics-vertical-line-spacing

the line gap, arent working anymore


also, i do agree on fontgautlet preview, it same in the general software like affinity.

preview on gautlet
gautlet.png
preview on affinity
affinity.png
preview on your tools, that its really big different
sdf.png
yours.png

As I told you before, fontgauntet uses its own line-height. You can adjust it with the UI. The third value from the upper left top is initially set to 1.05. You can increase or decrease it to your liking, but it does not allow you to test the default metrics for horizontal writing mode as defined in the font.