I read on UESP about the Anvil House, where if you store items in it before the renovation is complete, you will lose those items once the house becomes good again.

I was curious if this is the same for Deepscorn Hollow? I just bought a couple of the upgrades to it, but not all of them, and I haven't used the Ichor of Sithis in the shrine yet. If I store items in the house, will they be safe once I finish the quest with the Ichor of Sithis, and purchase newer upgrades?

Yes, they will be safe. Deepscorn Hollow is like the other houses, upgrading it merely adds additional things to the interior. The Anvil house is the exception because it completely changes which interior you load into, as opposed to adding things to the interior you always load into, which is the case for every other house.

Okay cool. Thanks for the reply.