Wikipedia:Use of non-free content survey/6

Policy changes that prohibit existing content
Changes to the policy on non-free content can be seen as disruptive, especially if content that was previously accepted is considered to no longer be valid. In some cases, such changes are legally mandated and must take effect immediately, and in other cases, the changes are internally motivated and some allowances could be made.

Assuming no legal urgency exists, changes to the structure or application of non-free content policies should apply to previously uploaded images: