Typically but not always:

Getting picked off alone is a map awareness/game sense issue.

Getting picked off in the backline is a positioning or mechanical error.

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Also as a side note, it’s good to be aware that you’re having bad deaths and getting caught out… but don’t lose focus on the goal. Winning. You can win and have a terrible KDA, especially as support.

If I can make a play where I die, kill the enemy adc, and my adc and enemy support lives… I’m going to do it. It’s generally winning. But my KDA will be fairly poor at 1.0, and if I do it a few times, I could easily end up with a 0/5/5 scoreline while my ADC is ~5/0, and up no small amount of CS/exp.

I’m basically winning the game, but I’m dying a decent bit and my KDA is bad. Enemy ADC might be something like 1/5/4.

Obviously it’s better to not die, but if someone has to die, it’s generally better the support dies to win the fight and not the adc.

Just a single example to illustrate the point; don’t focus purely on improving KDA. Focus on eliminating bad deaths.