I have the same issue even while seeding 50 torrents. Task manager shows uTor utilising a small amount of memory under "processes" but the actual used up RAM keeps increasing up to 13-14gb out of 16gb.
No such issue occurs with qBittorrent. The only reason why I haven't switched over is because qBit connects to less than half the peers when trying to seed.
uTor RAM/caching issue seems to be ongoing over several years, over half a decade!
Reading around shows that uTor devs will blame windows caching but does anyone know of any settings we can adjust to prevent this from occurring?