Take legislators as examples. Have they imposed constraints on you through laws and regulations that affect your solution design, or are legal requirements part of the quality requirements? That depends very much on whether you perceive 130 km/h on freeways as a restriction of your personal freedom or as a contribution to environmental protection, noise reduction or a reduction in the number of traffic fatalities.

Therefore our advice: Never argue about whether a requirement belongs to quality requirements or constraints. Simply record them so that the development teams can take them into account.