Updated to Drupal 8.6.4, which is PHP 7.3 friendly. Also updated HTMLaw library....

[yaffs-website] / web / core / modules / media / tests / fixtures / oembed / photo_flickr.json

{
  "type": "photo",
  "title": "Druplicon FTW!",
  "width": "88",
  "height": "100",
  "url": "internal:\/core\/misc\/druplicon.png",
  "thumbnail_url": "internal:\/core\/misc\/druplicon.png",
  "thumbnail_width": 88,
  "thumbnail_height": 100,
  "provider_name": "Flickr",
  "version": "1.0"
}