You can prefill a linked-record filter with a unique ID so the form opens with a filtered list. A URL prefill can be changed or shared; it does not authenticate the user. If users need access based on their identity, configure the appropriate login and record-access settings rather than relying on the prefilled filter alone. To prefill the filter, use these two features:
Prefill the filter fields. (the same way you would prefill a field on the form)
⚠️ When you try to filter linked fields, you should be prefilling the filter. Which should be a field other than the linked records field itself.