We thought we had resolved this with 🐛 Tiny Media Library Grid Thumbnails Active , but can confirm that thumbnails in the Media Library in both dialogs and the right sidebar are tiny. The problem presents with either Claro or Gin applied as the Mercury Editor theme.
Also check against 🐛 Thumbnails in medialibrary can grow too wide Active , which reported that thumbnails were too wide.
Active
2.2
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