Summary:
Some blocks (and parts of the blocks) placed outside the selected area in the structure block are displayed. The list of blocks below is displayed only next to the upper, eastern and south side.
List of blocks:

• Bed
• Lectern (with book)
• Conduit
• Spawner (with mob)
• Piston
• Shulker
• Chest/ender chest
• Enchantmet table
• Head
• Banner
• Item frame (with item)
• Bell
• Sign

Steps to reproduce:

1. Place the structure block.
2. Place these blocks next to the upper, Eastern and South Side near the selected area.

Observed results:
Blocks/parts of the blocks are displayed inside structure block preview.

Expected results:
Blocks outside the selected area are not displayed inside structure block preview.

Video:
Minecraft 2022-10-29 19-38-33.mp4

Screenshots: