The bug
Trees can no longer grow with blocks next to the sapling. For oak trees, only large trees can spawn if there's a block next to the sapling.
All blocks except dirt, grass blocks, logs, and other saplings are affected (see MC-15224).
To reproduce
Plant a sapling
Have any block next to it
Spam bone meal on it
→ ❌ The tree won't grow (or is a giant tree if an oak sapling was used)
Original description
Its impossible to grow trees with a dispenser on the next block to the sapling, preventing automation.
Even tall grass obstructs growth of the trees. Trying to grow an oak always require tonne of bonemeal and results in a large oak variety.
Growing other types, like birch, with any blocks around it would cause it to fail to grow.
Previously for a tree to grow, it required 1x1 space at the sapling, and 3x3 above, while for 2x2 trees it was 3x3 at the base and 5x5 above, and blocks like leaves, or logs won't obstruct it.
Many tree farm design followed these design principles for years.
Currently all the tree farms are broken as tree won't grow next to a dispenser, rendering that dispenser functionality useless.
Related issues
is duplicated by
relates to
Attachments
Comments

Can confirm. Does NOT affect dirt or grass blocks since MC-15224 is a thing.
I've added some more information I found out to the ticket, if I got anything wrong or missed something, please leave a comment.

Well my ticket https://bugs.mojang.com/browse/MC-164143 was closed saying it was a duplicate of this issue but it's worse than just nearby blocks. Many tree's seem to need sky access to grow now as even having no other block within 7+ blocks of a sapling will it grow via block light.
I could get single oak saplings to grow, as well any 2x2 varrient but all the others would not grow no matter how much space you give them if not exposed to sun light. Not sure if video's are allowed but I did this short one to demonstrate. https://youtu.be/Qu-fR93uJsw
If not here is a screen shot.
[media]
Can confirm the skyview issue (sub issue?), a single block at build limit will stop a sapling underneath it at sea level from growing.

The saplings in question also won't grow in the Nether unless a hole is knocked through the ceiling straight above them.
I have reopened MC-164143, it is a related but distinct issue.

Creative mode. Cannot grow a birch from sapling. Have tried in the middle of a field with no blocks nearby, in sunlight, spammed with bonemeal.
Snapshot 19w42a