4k Video Compression loss?

I have about 8Tb of 4k footage from various projects throughout the years. Most of these will never be used to re-edit. The projects have been released. I've kept them for nostalgia. I sometimes go back and rewatch the footage to relive that particular set and working with that group of people.

I'd like to try to reduce the storage weight of this old footage. I'm considering compression. How much quality loss am I likely to experience?

Primarily I'm hoping to get insight on if my use case is a good fit for video compression, and what the possible consequences are. Thanks!