It's not for 1.10. The mod is just numbered that way i.e., 1.12.2-2.1.10 and it worked fine in forge 1.12.2-14.23.4.2759 (the last forge I used) and the 300 forge versions before that as he hasn't updated his mod since 2017. Right or wrong, something just changed in the Forge code to cause this.https://minecraft.curseforge.com/projects/better-foliage/files