Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 391.01
Broken: version: 2.80 (sub 71), branch: master, commit date: 2019-05-22 17:52, hash: rB8fdbd1377e53
Short description of error
Linked curves (CTRL+D) with curve modifiers are not deformed correctly with this button enabled
Exact steps for others to reproduce the error
Here's a file that shows all the problems above:
Literally try CTRL+A on any of them.
Also see the strange behavior of the "linked curve".