Strange character string in dwg exported text from LO v8.0

[unearthed]

I've just exported a vector layer of labels to dwg from LO (made in SU8 using TIG's Add Height from Datum).

In LO the labels are formatted like so: ~ -0.30m (and in the resulting .pdf)
but in the dwg export they're : \c4144959; ~ -0.30m

Does anyone know where this string comes from?

[update] I've checked the source dwg and it does not contain the string.