I understand the lore of species aging differently. Honestly that was kinda clever. What bothers me is how storywise the writers just keep wanting to have their cake and eat it too. He's literally a man/baby who is both old and young as the story demands.
He will be a cute clueless baby in one scene, a comically effective force warrior in the next. An idiot with no attention spam whatsoever in one moment, and in the next, perfectly able to read the situation and use the force (for humans this takes deep intention and focus).
The writers milk the cuteness of his dependence on Mando, but desperately want to avoid the audience thinking about how messed up repeatedly bringing a dependent into battle is.
What if 'baby yoda' died from a blaster bolt to the face (won't happen because of plot armor but Mando doesn't know that), would he be considered a willing combatant? Or could the New Republic charge Mando with absolutely gross child endangerment? Lol