Repair for tub surround and vinyl floor seam

New user here, with a "new to me" house. I've got the normal fiberglass bathtub/shower surround and a sheet vinyl floor. Problem is, the seam between the two is not covered with anything, no caulk, nothing. I'm afraid to leave it like this for water may get in the seam and ruin the floor, which is gyp-crete due to radiant floor. What do I do to seal the seam between the tub and the vinyl floor?

Thanks in advance for the advice.

You need to immediately get some tub/tile caulk and caulk that seam. If moisture gets under and causes the edge of the vinyl to curl, you will never get it flat again.

Caulk would work. There's also a plethora of moldings and cove bases that would also do the trick