coolant disappearing from reservoir but not leaking

What is your question?

We keep having to add coolant into our reservoir; usually 3 times a week. It's not leaking and we only drive it around 50 miles a week. The overheating indicator warning has come on twice (with the temp gage going all the way to HOT), interestingly only when the cruise control is on (maybe coincidental but thought I should point it out). We are planning a 1600 mile trip next week and wondering if this is a huge issue. The radiator is completely full.

How long has your 2016 Toyota Sequoia had this problem?

A few weeks