Is it frowned upon to use someone else's fo as inspo for your own pattern?

I can see it from both sides and I'm curious what you guys think.

I had this idea for a new project. One google search later, I found someone had already made it (shocker I know). I figured I could look at their fo as inspo and reverse engineer it to make a pattern for myself to use.

So here's what I'm wondering:

Would it be wrong to post my pattern online?

Would I need to credit the inspo if I do?

Any advice is appreciated!