I've attached images. Not sure if I should just paint over it with epoxy or replace it entirely.
That sticky tape has to go! it's not helping at all,
so rip that off, and then poke at the wood with a hard tool like a skewer or a screwdriver to see if it is soft like bread or hard like wood.
if its hard it's still good.
if it's soft rip out the soft parts
the cause seems to be that the synthetic siding hasn't been installed between the windows,