System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.66

Blender Version
Broken: version: 2.92.0 Alpha, branch: Unknown, commit date: Mon, Nov 16, 10:10 PM, hash: rB797dfa6a0a7d5d2bf62bdc03cf619addbc9e1064
Worked: Not introduced by, but now possible to occur by D7602: NLA: Fix Sync Length

Short description of error

When strip B is Sync Length-ed and the left bound is past the start of the transition, then all strips to the right of the transition are offset instead of all the strips to the left of B. D7602: NLA: Fix Sync Length allows this situation to occur.

Exact steps for others to reproduce the error

Open the attached blend file.
Enter tweak mode strip B
Move the left most keyframe to frame 20 (past the start of the adjacent transition)
Exit tweak mode on B
Sync Length on B
~Error situation (the video shows that transform operators easily break in this situation)