It's related to different routing tables. RouterOS v6 had it like this:
/ip route
add dst-address=x.x.x.x/x gateway=y.y.y.y routing-mark=tablename
Current v7 uses:
/ip route
add dst-address=x.x.x.x/x gateway=y.y.y.y routing-table=tablename
But in early v7 they had horrible idea to use this:
/ip route
add dst-address=x.x.x.x/x^tablename gateway=y.y.y.y
Luckily it was scrapped, but as you discovered, it partially survived in WebFig. It's a display bug, there should be separate column for routing table name, as is in WinBox. But since WebFig generally seems to have low priority, they didn't fix it there yet. The @1 is something similar, it's a valid config if gateway is in another routing table, but unless you have routing table named "1", it's probably also some display bug.
You should send a bug report to get it fixed:
https://mikrotik.com/support