With the currently latest version of ConTeXt LMTX 2020.11.25 21:42, this MNWE fails with the following error message:

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\setuptagging[state=start]
\starttext
\obeyspaces\obeylines
  patch
\stoptext

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tex error       > tex error on line 4 in file ./scratch1.tex: Valid keyword expected, likely 'plus'

<line 3.4>   pa
    tch

1     \setuptagging[state=start]
2     \starttext
3     \obeyspaces\obeylines
4 >>    patch
5     \stoptext

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This may be a bug in the tagging feature.

Cheers,

Christoph