I'd like to ask rather some basic questions regarding "uncomputation".

I understand the operation itself and returning the garbage bits back to the original product states .. etc. But I wonder if there is a simple example that shows any issue if we don't do "uncomputation"? Does it lead to wrong results if the circuit continues carrying these "garbage bits" to the end? I see the algorithm like HHL has the uncomputation in the end also. I looked around the textbooks and youtube etc. I couldn't find any good resource to show why the uncomputation is important.

Thank you for your kind help.