It’s relatively common for various national and regional GNSS correction networks to be referenced in a CRS other than WGS84 used in OpenStreetMap. The reason for this practice is that countries and regions use their own coordinate systems, most suitable for the territory they cover.
For example, the Oregon Real-Time GNSS Network (USA) uses NAD83 (2011) epoch 2010.00, according to their website.
It means that any RTK measurement taken while receiving NTRIP correction data from such a network will be referenced to the same CRS. That applies directly to the NMEA data output of the receiver, despite it normally being implied to be in WGS84. The majority of receivers available to amateurs are incapable of being configured to be aware of that. (The only sub-$1k receiver core I’m aware of that can “understand” the NTRIP CRS defined manually is Septentrio Mosaic.)
So, unless you perform a transformation from said CRS to WGS84, your tracks are going to be completely unsuitable for submission into the OSM public tracks database.
However, there’s a pretty straightforward way to perform the required transformation. Unfortunately, it’s “a little” longer than ideal for the exact same reason that NMEA data is implied to be in WGS84, so feeding a NMEA log directly may result in the reader ignoring the input CRS override.
The key tool for this is, coincidentally, JOSM. Here’s the workflow that functions just fine in my experience:

