math rendering problem with \bar, \vec and possibly others

[tosione]

Describe the bug
When using math equations with \bar or \vec with subscripts, the equations are not rendered correctly in some situations.

To Reproduce
Type at least two variables with \bar or \vec and subscripts that have letters embraced by { }, and the rendering will fail.
In order to render correctly, only the first one could use subscript with { }.
If a space is used in front of the first subscript with { } it seems to render correctly.

Expected behavior
I expect all the formulas to be rendered correctly.

Screenshots
An array of examples of what works and what doesn't is shown in the following picture:

Device

• OS: Windows 11
• Version 25H2
• App Version 2.6.10

[PathGao]

Retested a display formula containing \bar{x}, \vec{v}, and \mathbf{F} against the current v2.6.14 source build on macOS. It renders correctly in split preview. Please retest with a current build and attach the original formula if a specific expression remains broken.

[tosione]

I did the test again with 2.6.14 and got same result:

I attach test file:
test.md

[PathGao]

Thanks for the minimal test file. I reproduced the second and third equations on v2.6.14, traced it to Comrak turning paired underscores inside $$…$$ into Markdown emphasis, and opened #326. An isolated macOS release bundle passes all five formulas from the attachment.