Also agree with this, but want to caution: Bring this up as gently as you can

Don't accuse them of being ADHD, or insist too strongly

If you do bring it up, I would say make sure to really emphasize that you don't think they need fixing. It's something that might help them overcome their own struggles, not something to make them a better person for others, you know?

"I have always envied your ADHD hyperfocus superpowers." /h

Everything I am really good at, I am really bad at, depending on context and the wobbly compass that governs my internal motivation.

It is definitely not all bad. Without my hyperfocus, my life would be unrecognizable. I would be unrecognizable. Hyperfocus is core to so many things I am good at, care about, and have achieved.