Hey,
When a user gets stuck and just wants to figure out what went wrong in their code, it's super frustrating that clicking "View Solution" just wipes everything and shows the answer. That’s not a great experience. It seems to user like they were waste their time and doing wrong implementation. Which leads to less motivated.

It’d be way better if, when the user clicks "View Solution," a popup showed up with two editors — their code on the left and the actual solution on the right. This way, they can compare both, spot the mistake, and learn from it without losing their work.

It helps them stay involved and actually learn instead of just copying the answer. While there will be copy button to copy the solution but there is one layer more to restrict the user.

Here is video for better understanding

Just rough view of suggested design of modal or pop up to compare the code