HenryNY: Not sure exactly what you were taking about. However, in order for GOG to verify your installation, a reasonable expectation is that GOG has to download enough data based on what you wish it to verify. And for a massive game like BG3, whose installation exceeds 100GB, a download of175MB data - less than 0.18% of the total size of the game - seems to be very reasonable.
Nothing unexpected here.
It's not that it downloads files, it makes no difference to me how many gigabytes they have. What I mean is that after installing these 175MB. If I check the files again, the situation will repeat. It will download and install 175MB again.