This is regular infantry? OK, it has been a problem with nomenclature then.
Regular infantry, in this war, is only used to hold trenches, do rear work, or secure the flanks of assault formations.
They will do everything they can to avoid assaults, down to self harm, or desertion. It's not what they signed up for. In many instances, they were given assurances by recruitment staff that they would never be put in an assault position.
Men on assault get better equipment (most importantly communication equipment), specialized training, higher pay, and are typically younger and more fit.
On the penal battalion side we had two types of assault units. Storm-Z and Storm-V. Storm-Z get pardons after 6 months of service, but have a mortality rate of effectively 70%. Storm-V do not get pardons, but have to continue to serve. They are assigned less suicidal missions.
Within a regular Russian motorized rifle batallion - the assault component can be as small as platoon sized or as big as company sized. So 30-40 men, or 70-90. These are handpicked among the battalion's riflemen.
They are equipped liberally with electronic countermeasures. Trained in motorcycle or ATV tactics. And are issued specialized light weapons.
Essentially modern light cavalry.
Not in Wojsko Polskie
In the Russian army of 2022 there was also a much higher proportion of servicemen who were capable of engaging in assault operations. Most of them are now dead or wounded.
You need to imagine what the quality of Polish infantry would look like in year 3 of industrialized warfare. You would be searching for assault capable men with lanterns during the day.
Were those Koreans successful? I mean, did they actually manage to take several Ukrainian positions
Do you see any Ukrainians in Kursk?