A motion to suppress evidence certainly may be filed to suppress evidence obtained by police during a detention (as distinguished from an arrest). After all, during a detention, a suspect is not free to leave, so police searches are possible and some may even argue probable. To read a summary of a reported decision that allowed such a motion to suppress, click on the following link.
https://www.greghillassociates.com/motion-to-suppress-granted-after-unlawful-detention.html