Interesting Cursor Position Bug

[amadeus]

Describe the bug
When using vim fugitive to make commits or push, the cursor seems to jump around - it's almost like a strange rendering artifact. I've attached a video:

To Reproduce
Detailed steps to reproduce the behavior:
It is the result of a plugin vim fugitive - but not sure how to replicate without it, I imagine this shouldn't be related to the plugin itself, but perhaps an issue with echon or something?

Expected behavior
I expect the cursor to not move around and end up not where it should be? You'll notice it's as if it's position is lost. Once I try to move the cursor, it returns to it's original position

Screenshots

CleanShot.2021-09-15.at.19.16.52.mp4

Environment (please complete the following information):

• Vim version 8.2, patches: 1-3423
• OS: macOS 11.6

[eirnym]

I found it a bit laggy lately on my arch Linux box. I'll test it tomorrow again

[amadeus]

Did a bit more digging, looks like it also can repro in normal Vim matsui54/ddc-source-buffer#8

I think overall, there is probably some deeper vim bug around reacting to BufReadPost, but it seems like too much work for me to try and find a repro case for, so I did figure out a workaround within that plugin