Yeah that can happen with vaccines, because you aren't actually sick, it's just your immune system overreacting to something that it thinks can make you sick. This does, however, give you symptoms you associate with illness. Your subsequent covid infections - during which you are actually sick, with something that can cause you actual permanent damage and death - are considerably less severe because you took the vaccine.
That really sucks it fucks you up for an entire week though, it's only a day or two for me.