I feel this is one of the most popular when it comes to blame on a certain group of individuals. Because something happened that was not favorable.
I agree to everyone above and I would like to add my two cents here as well from experience and what others also went through as well.
When you did do this spell did you follow the “ABCs”? As in shielding/wards, banishment and centering your self? When you decide to make this spell did you do research on the person first before evoking them? Did you write out your spell and fixed or add anything? Did you send at least some time to prepare your body and mind for the spell? Especially the latter is important. We carry things with us all the time from the outside world. From physical to more mental. So if you don’t prepare your body and mind it can affect your spell. A lot of the people that have been doing this either from here or outside can tell you the exact same thing.
So let’s say you did do these things and still had this out come. The first thing that came to my mind is parasite. These things can come in many forms and sizes. They can do from just annoying bug thing to full out drainage even causing some damage to your astral even physical being. Now with these you can get them anywhere and anytime. But you are more susceptible to these things when your the most open such as a spell or evocation/invocation. When you do these things or a spiritual practice you open your self to the other worlds. This can be an easy target for parasites to get to you. Even when your working with more light sided things you can still get them. They are in a sense like the flu or in this case COVID. In the way that you can have your vaccines and follow the safety guidelines and still get it. The only difference is it won’t be as bad and I take into count that I had work with angelics and other light energy before and only a year ago I found out I had a parasite that has been with me for years.
So it does not matter if your working with dark or light or gray or green or what not energies, they don’t care because they just care about your energy.
With this I suggest looking a bit deeper at what happened and why. This is a learning experience and well when practicing magic at all to this context of actually working with energy let alone other beings you will have accidents. You will have moments when something will blow up in your face like in the science lab. But it’s part of the journey. No matter who you work with or call on you’ll face challenges. So really look on this as one and again ask questions, why, who and what can I do to improve it? Magic itself is not just casting and seeing epic cool things. It’s a science and a art in one.