Server version: 1.21.4
Shopkeeper version: 2.23.4

EXAMPLE:
If you want to trade to get ONLY orange wool, you will get orange wool and red wool holding the SHIFT key
This only applies to villagers from shopkeepers (in the previously versions holding shift worked the same as in default villagers)
Some players are nervous because they get unwanted trades and lost items

I just tested this but cannot reproduce the issue:

• Spigot 1.21.4
• Shopkeepers 2.23.4
• The same trading recipes as in the screenshot.
• No trade explicitly selected on the left side, only emerads input manually.
• Tested with both admin and player selling shops and different stock levels.

Observed behavior with enough/infinite stock: I get 4 stacks of orange wool. With limited stock in the player shop: I get as many orange stacks as are available.
In neither of the tested cases I received the red or yellow stacks.

Please try to reproduce the issue:

• On an up to date Spigot server if not already the case.
• Without client side mods.
• Without other server side mods that might be interferring, especially protocol related plugins.

The only "issue" I noticed was that the trade was no longer automatically marked as "out of stock" unless the player exits and re-enters the trading view. However, trading was still prevented in this case. And even when there is no stock of orange wool and I insert the currency items, Minecraft/the Shopkeepers plugin would not automatically trade for the other trading options (the player would need to explicitly select one of the other trades in this case).