If you run

\starttext

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
$\overbar{OA} = 4,2$
\stoptext

Then the overbar has the bar in a very long altitude.
Can you please, see the output attached.

Thanks in advance,
Xavier

PS: I use context version:mtx-context     | ConTeXt Process Management 1.04
mtx-context     |
mtx-context     | main context file: /usr/share/texmf-dist/tex/context/base/mkiv/context.mkiv
mtx-context     | current version: 2023.03.10 12:15
mtx-context     | main context file: /usr/share/texmf-dist/tex/context/base/mkxl/context.mkxl
mtx-context     | current version: 2023.03.10 12:15
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / https://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : https://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : https://contextgarden.net
___________________________________________________________________________________