When I open in QGIS a new project and I add a Openstreetmap Basemap, the Project CRS is set automatically to EPSG:3857.
I have a specific Shapefile representing a State boundary of an African country: when I import the file the software ask me to choose which CRS use. Selecting the same of the project (ESPG: 3857) the Shapefile is not aligned correctly. I tried to export the file, selecting the correct ESPG but the issue persist.
I also tried to Reproject layer, but doesn't change the outcome.