We can’t reset your password because it was changed within the last 24 hours Exception in Salesforce occurs when “Require a minimum 1 day password lifetime” is enabled on the Profile. Disable it if it is not needed. Salesforce Admins can reset the password though this is used.
 

Also, check Last Password Change or Reset on the User Detail Page so that user can try after that to reset the password.

Reference Article: https://help.salesforce.com/s/articleView?id=000333679&type=1