"between the drip edge and fascia?"

Which board are you asking about?

Looks like a piece of flashing/ flat piece of galvanized metal? Maybe something caught there from the time the roof was installed because the drip edge is wonky in front of it.

I’m confused too. The board with the red mark, the board with the yellow mark, or the boxed-in-blue thing?

I take it as littlebug's blue highlight ^^ is the board you are questioning. Guessing from the 3/4" thick hanging board and deep shadow behind the metal drip edge, you apparently have an additional fascia detail added onto the primary fascia - often a 1x2 or 1x3 is used. However, the metal drip edge was chosen with too long a leg (or a 1x4 or 1x6 "crown" fascia should have been used) which extends past this board. It and your main fascia might be falling off the rafters tails because there is wood rot. If so, adding a 2x sub-fascia between rafters would allow a nailing base for both fascias.