Similar to how wool blocks vibrations from reaching nearby sculk sensors or sculk shriekers, it would block sound from reaching the player if the sound source is been covered up, or if the player stands behind wool. This would be useful, for example, in redstone contraptions that produce a constant ticking or piston sound. 

If you like this idea, please vote for it on the official Minecraft Feedback Page!
Wool Should Block Sound – Minecraft Feedback

The colour of poplar leaves should be randomised when placed, not when grown.

The item texture would be a sapling with all the colours. When placed, a yellow, orange or red sapling would be chosen at random. Rather than wasting time or bone meal on the sapling just to get an unwanted leaf colour, you would simply pick it up and place it again (as you would with paintings). 

If you like this idea, please vote for it on the official Minecraft Feedback Page!
Randomise Poplar Leaf Colour on Placement – Minecraft Feedback

Thanks for reading :)

The Minecart With Furnace Rework

As things stand now, the minecart furnace has one of the worst implementations possible and is not used at all. Moreover, the minecart is, since the elytra was added, not worth using and building an infrastructure for.

General changes

Chained Minecarts
Minecarts (every version of it) can be chained together by applying iron or copper chain in the same way as you would leash boats together, forming a solid connection between each cart.

Why chain?
In order for the train to work properly a solid connection is needed. When one minecart is being driven, the ones in front of and behind it would run at the same speed without touching or pushing each other.

Chained minecarts running over a curve

Powered rails
Powered rails do not longer determine the speed to 8 b/s; they run the minecarts at their speed without requiring player input. The speed is instead defined by the minecart.

Example 1: A minecart has a max. speed of 8 b/s. If it runs over a powered rail, it will run at 8 blocks per second without requiring player input.
Example 2: A minecart with furnace and a lava bucket as fuel has a max. speed of 19.5 b/s. If it runs over a powered rail, it will run at 19.5 b/s without requiring player input.

Minecart with Furnace

The fuel determines the speed the minecart with furnace runs at. Tu run, it requires player input via chained minecarts or running or powered rails. If pushed, it moves a litte, but not at its defined speed.

A new interface shows the player how fast the minecart with furnace can run with a given fuel.

Every fuel gets used up after 1600 ticks (1:20min).
If there is no fuel in it, the minecart with furnace is unable to move (unless it's pushed).

The speed of the fuel is closely related to its "smelts per one" number (for example, 1 Lava Bucket can smelt 100 items). The steps up or down to the next fuel from "smelts per one" are relatively the same size as the steps up or down from the "speed".
^(There are some minor parity differences between Java and Bedrock with) *^("smelts per one")*^(, so I used the numbers from Java as they seemed more logical) *^((for example, slabs can smelt fewer items than a block))*^(.)

list of \"smelts per one\" and \"speed\" of any fuel

The max speed is set at 19.5 b/s, so redstone components such as the detector rail still work (the game runs at 20 ticks per second).
A minecart with furnace fuelled by coal/charcoal runs at the same speed as a normal minecart (8 b/s).

EDIT: As suggested in the comments by only_Q and Eclipse_58008, furnace minecarts should be able to load chunks, so you could use them as delivery trains.

TL;DR

just read the post image :)

The Minecart With Furnace Rework – Minecraft Feedback

I don't know what Mojang aimed for or if it wasn't even intentional, but they should adjust it as they did with the straw bale.

The problem is the wither's head being 8 pixels wide, so there's no center point for the 3-pixel-wide body. I suggest widening the body to 4 pixels and correcting the symmetry of his "arms".

I can't unsee it now :(

Edit: As suggested in some comments, the wither should be made even more asymmetrical so that it keeps its threatening and abhorrent appearance.

How it works
As soon as a TNT (or a sulfur cube filled with TNT) is ignited within range of an allay (with or without an item in its hands), it rushes to cancel the fuse before the TNT explodes, turning it back into a normal block of TNT. If the allay gets hit by the explosion, it doesn't take damage but gets thrown away a little bit instead.

Why do I think this feature is needed?
Especially with the sulfur cube added, if you are the victim of a TNT attack, you have hardly any chance to defend yourself. The allay would act as an active defense for your base or build, but still wouldn't make TNT attacks impossible. It also gives the allay a much-needed and deserved purpose to be freed from his pillager prison.

Why the allay?
The allay is one of the most overlooked mobs in the game, and this would give it a needed fresh overhaul without hurting its existing mechanics. I think this feature fits the allay well, as it is a helping and peacful mob.