At log level notice you should be getting a line per transfer and a line every 60s showing statistics. No way that should add up to 25 GB! Maybe you had it on DEBUG earlier and changed it?
I think you are likely correct. I was having issues a while back. I think I did have it on debug and changed it back not realizing the log file was huge until now.
I found this issue when looking for the reason why my system drive was full. I use a smallish SSD as a system drive.