Looks like that tomato was damaged and is now spoiling.

Agree. That looks like mold, not a web. Is it affecting a lot of other tomatoes, or just the one? If just the one, don't worry about it. If there are multiple tomatoes affected, you need to figure out what's damaging your tomatoes and letting mold set in.

If the bites look like there are teeth/gnaw marks, it could be a rodent like a squirrel or rat, maybe an opossum. If the tomato is still on the plant, it's unlikely to be a raccoon.

If the damage has strangely surgical looking edges like the picture in this person's post, it's a hornworm. Although they're "just" caterpillars, they get really huge and do a surprising amount of damage.

Sent some stuff to the county extension office and they think there are two problems - squirrels or birds getting the ripe ones and then a fungal pathogen shown in the picture here. They recommended netting over the top and treating with a fungicide so I'm giving that a shot.

I don't think you'll need a fungicide if you stop the critter that's eating your tomatoes from damaging them and giving the mold somewhere to grow. But it won't hurt anything.

Squirrel and bird damage look very different. Bird damage looks like someone has stabbed your tomatoes. Squirrel damage looks like something has chewed your tomatoes. Bird damage also tends to be on tomatoes that have turned color, whereas squirrels and other rodents will go for green fruit as well.

Some birds can often be stopped by putting out some water, as many of them eat tomatoes when they can't find water. There aren't that many birds that prefer tomatoes, although mockingbirds are notorious tomato eaters.

Netting will work for many birds. It's less effective on determined rodents.