Minecraft
Banner Designer
A loom shows you the result but not the command, and a banner worth keeping is a banner you want to hand out. Design it here and take the /give line.
1.20.5 replaced item NBT with item components. The two syntaxes are not interchangeable — a server rejects the wrong one outright.
Layers, bottom of the list on top
A loom applies six layers at most. More than that is only possible through commands, and the banner will not be repairable or copyable in game.
Preview
Your command
/give @p minecraft:white_banner[banner_patterns=[{pattern:"minecraft:stripe_bottom",color:"red"}]] 1How this works
A banner is a base colour with up to six pattern layers stacked on top, each with its own dye. The command encodes that list — and this is the second place the 1.20.5 change bites, harder than elsewhere: the modern form names patterns in full and colours by name, while the older NBT form uses two- or three-letter pattern codes and numeric colour indices. They are not interchangeable and mixing them produces a plain banner with no error.
What people get wrong
The preview draws the geometric patterns accurately and cannot draw the texture-based ones — creeper charges, skulls, the Mojang logo — because those are artwork rather than shapes. Those patterns are marked, and they are still correct in the generated command. Note also the six-layer limit: it is a loom limit, not a game limit, so commands can exceed it, but a banner with more layers cannot be copied or repaired in game.