A few bugs I found while playing on survival

Gold cannot be smelted
Gold ore, Nether gold ore, and Gilded Blackstone cannot be smelted into their counterparts

Fortune is broken
No version of fortune works on any of the ores

Horse and Donkey Duping
Once a horse with a saddle and whatever type of armor on them dies, they drop two saddles and two of the armor. (Some horses seem incredibly fast, though I don't use horses often, these are the opinion of friends)
This also applies to donkeys and their chests and is much more broken. Any item put into the chest, upon the donkey's death, everything is doubled. This also applies to the carpet put onto a llama.

Invisible suffocating blocks
Any block that can be broken quickly such as netherack, ice, and stone can appear broken for whoever "broke" it. They can also suffocate in these blocks and cannot break them again. Sometimes they will re-appear if clicked on or updated but normally stay invisible until a re-log. This also happens in plants like potatoes and nether warts.

Mobs into nether portal cause corruption
If to many mobs go into a portal (only overworld to nether, without another player there to load them in as they go) it will cause permanent corruption to that chunk and will crash if even loaded within render distance.

Crimson and Warped a little off
Crimson and Warped wood cannot craft wood tools, smithing tables, lectures(out of the slabs) and there are a few others. They also do not show that you can use them to craft things like a piston but you can if you make it manually.

Fire is broke
Fire seems to never actually burn anything and stays lit forever, causes some lag and have random forever fires around the world

Mob spawns and Lighting
I am aware of some of the changes to the spawning algorithms for the hostile mobs, but it seems as though they are spawning directly in our light sources. Countless Villagers have died and many, many creepers have spawned in, or right next to our homes because of this.

Minor Furnace UI
The arrow showing how much more power you will get out of a coal can sometimes get stuck and/or be incorrect

General Lag
This was causing some redstone to be a bit difficult, especially slime blocks and positions. This also made eating a bit tedious because you couldn't eat the food in the correct time. Anytime someone was mining in the nether it would cause tremendous lag for everyone else, especially if they were mining very fast and/or leaving a lot of items on the floor.

Other issues
Had some problems with villagers and them changing professions after being traded with, or just them having extreme difficulty pathing to their beds and workstations. Mounting off of Striders has proved very difficult when you want to jump off of their back onto a block they are eye level with(I have died in lava a few times for this).