I have a note on that tutorial for this very case. If the map you are trying to georeference uses a projected CRS that you know of, but the graticules labels are in a Geographic CRS (latitude/longitude), you may use an alternate workflow to minimize distortion. Instead of using a Geographic CRS like we are using here, you can create a vector grid in QGIS and transform it to the projected CRS to be used as a reference for accurate coordinate capture. See this post for step by step guide

https://raisedbeaches.net/2018/02/01/georeferencing-in-qgis/

I have a note on that tutorial for this very case.

"...If the map you are trying to georeference uses a projected CRS that you know of, but the graticules labels are in a Geographic CRS (latitude/longitude), you may use an alternate workflow to minimize distortion. Instead of using a Geographic CRS like we are using here, you can create a vector grid in QGIS and transform it to the projected CRS to be used as a reference for accurate coordinate capture..."

See this post for step by step guide.

https://raisedbeaches.net/2018/02/01/georeferencing-in-qgis/