So I'm playin on SevTechAges Modpack and I created the portal and when I'm using a moss to change the biome in the dimension It's not working but the message about changing the biome appears

The initial suspicion seems to be correct. SevTech has some mods that completely replace how biomes work unfortunately.

Thanks for the issue report. I have been getting this reported a lot in relation to the SevTech ages pack. I believe that one of the mods in the pack is messing with how biomes are being retrieved by the game. I will keep this issue open and use it as a hub for updates on gathering info. If you have any log files related to this issue that would also be very helpful.