Before making a potentially impactful IP block (especially when an IP range is involved), it is a common practice to review (logged out) contributions from those addresses. Once temporary accounts are deployed, this workflow will no longer work, as Special:Contributions will only allow users to display contributions from a temporary account, not from an IP address or similar. This means that for a collateral damage check to be done, a CheckUser would need to be consulted. This is already the case for hard IP blocks (which affect logged in editors), but enabling temporary accounts would widen that even to soft IP blocks.
This issue can be resolved by making Special:Contributions take an IP address or an IP range as a valid input. Upon submitting, it would display all (unregistered) contributions from that IP address or that IP range, which is the same as the current behavior. With this feature, administrators would continue to be able to do collateral damage checks across temporary accounts, if needed.
Special:Contributions should only show temporary account contributions for IP addresses/IP ranges if the currently logged-in user has sufficient permissions. What permissions would be necessary for this level of access is not yet clear, and should be set by future discussion. It likely doesn't need to be the same threshold as we currently have for Reveal IP (see policy), and it might be more strict. Personally, I think sysop and above would be a reasonable restriction.
In short: The task calls for queries such as https://cs.wikipedia.org/wiki/Speci%C3%A1ln%C3%AD:P%C5%99%C3%ADsp%C4%9Bvky/2001:718::/32 to continue working (just across temporary accounts), assuming the user has sufficient privileges.
This task is likely similar to (or a duplicate of) T356290: Return local contributions by temporary accounts given an IP address or range.
This proposal was discussed with @SCherukuwada prior to filling the task.
