The pressure from Biden Administration was to mobilize from 18 upwards. Zelensky refused.
To me this suggests extreme losses on battle front of Ukrainian Army. Generation 25+ decimated. Much more losses then written or reported, I assume.
The aim is to expand the pool of fighting-age men available to help a badly outnumbered Ukraine in its nearly three-year-old war with Russia.
apnews.com
Ukraina lost 25% of population due to emigration to other countries.
Dropping mobilization age to 18+ (with similar losses) will make demographic catastrophe for the country in next decades.
With deaths outnumbering births nearly three to one, officials are seeking ways to encourage Ukrainians to return and boost the declining population.
global.espreso.tv
Demographic catastrophe, does not mean it will be stopped or further prevented by the seize of hostilities.
After the war, if economy is destroyed, infrastructure destroyed, or later "privatized" (a process known to transition countries) economic emigration will continue affecting working age generaton, because of lack of job opportnities.
This happened in Croatia, and is happening elsewhere in "transition" countries.
Before the war for independence,
we had almost 5 million people. After the war won, we joined EU, infrastructure and industry,, factories and other economic base was privatized, and we started loosing people due to economic emigration. Entering the EU speaded up the process.
Now demographic is unsustainable,
we are down to 3.7 million population, with average age growing rapidly. We started with issuing 50.000 working visa per year, (from non-eu countries such as India, Nepal Sri Lanka, Fillippines), and now we are at 200.000 working entry visas annually. Most of legal immigrants, work under contract, very hard, often for small money, support families at home (sending money home from our finacial system), and presumably will one day return home. But they are integrated in society, and cause no problems.
However demographic problems remain.