So i just coded a new vein in kubejs for ancient debris, which should spawn in the nether. It appears in game as one of the veins the machine can drill, but I feel like I've just spent an hour exploring thousands of chunks and didn't find it. Is it normal for it to be rare ? Did I forget smth ? How can I (if possible) find a vein faster ?

If you are on 1.20 you can use /coe locate <id> command. You have to adjust the spawning properties to change it's rarity (increasing the spawning weight value on 1.19 or older, or tweaking the .placement(<spacing>, <separation>, <seed>) values on 1.20)

thank you ! I changed the separation and placement value and they seemed to appear much more often