Travel mode freezes cloud activity on that sender so LinkedIn does not see an impossible-travel signal. The dialog says "Freeze cloud activity while you travel to avoid impossible-travel signals."
Freeze activity
Use travel mode when you, or the person who owns that LinkedIn account, will be in a different place than the assigned country.
Open the sender.
Select Set travel mode.
Choose a duration: 24 hours, 3 days, 7 days, or 14 days.
Add a note if you want. The note field is optional.
Select Freeze activity.
Unibox may show that the sender is in travel mode until the end time. Campaigns and Unibox replies from that sender stay frozen. This is not a campaign pause and not the kill switch.
Clear travel mode
When you are back, open the sender menu and select Clear travel mode. You do not have to wait for the duration to end. If Unibox still blocks a send after you clear it, the banner is naming a different Account Protection reason.