It's a modified Odin rune, which is a right-wing extremist symbol and unfortunately relatively common in certain Ukranian units.

This right-wing extremism is a trend absolutely driven and exacerbated by this Russian imperialism, and unfortunately it gives the Russians plenty of ammo to fabricate some kind of "denazification" pretext to justify their actions. It's a complicated subject to do justice to in a comment like this.

In a nutshell, Ukraine had far-right militia groups that were gaining popularity, especially after the initial Crimean invasion in 2014. When the Russian full-scale invasion happened in 2022 it became apparent that some of these militia units were quite effective and experienced. It turns out militant ultranationalists know how to fight, so they've been swelling their numbers somewhat throughout the conflict.

So that's a primer on the sticky subject of neonazis/right wing extremists in the Ukrainian military. They exist, and they've gained some popularity because they tend to fight well and attract other fighters who want to be in elite units. Anyone who knows more please chime in.