Is there a word/phrase/expression to describe a seemingly easy problem?

I remember my lecturer a few years ago using a word/phrase/expression to describe a seemingly easy problem that is actually quite hard to fix (e.g. if a football team keeps losing games, everyone looks at the problem and goes "oh, well just replace the coach and that'll fix it", when in reality the problem is much more complex/nuanced than that).

Hopefully someone can help!

Solution 1:

"Easier said than done" is a current saying for a seemingly easy problem that is actually quite hard to fix.

If you say that something is easier said than done, you are emphasizing that although it sounds like a good idea in theory, you think it would be difficult to actually do it. Collins

• Avoiding mosquito bites is easier said than done.
• I know I should stop thinking of her, but that's easier said than done.