Who is "they" and what is "clearly"? They are running out of men they can find to fight, and for quite a while the government and military used very aggressive methods to force men into service. There is a huge desertion problem, in the military and the country itself. A whole lot of Ukrainians do not want to fight.
I guess you're right. Ukraine should let Russia exterminate the Ukrainians. 3 times as many people will die as died in the German extermination regime, but it's worth it to avoid conscription, right?
A whole lot of people don't want to fight in any war.
What matters is the relative portion. Though they my differ in the views as to whether the lost regions can be regained, or on what terms a cease-fire may be acceptable -- by all indications, a very solid majority of the society in non-occupied Ukraine supports the fight.
Who is "they" and what is "clearly"?
About 60-80 percent of the population. "Clearly" as in according to reliable polling data I can pull up later. Or by spending any amount of time talking to Ukrainians.
There is a huge desertion problem,
It is obviously a significant problem, but a better source is needed on the "huge" part. The link you provided does not support that view.
If I hear "desertion is a huge problem", what comes to mind it the situation in Afghanstan after the notorious Trump-Biden pullout. The situation in Ukraine is nothing like that, not even remotely.
https://nationalinterest.org/blog/buzz/ukraine-running-out-s...