Is UltraClear epoxy flammable or fireproof?

It isn't flammable, but it isn't fireproof either.

UltraClear epoxy products are not flammable. Once cured, the epoxy is an inert, hardened plastic.

That doesn't mean it can take heat. Cured epoxy is not designed to be exposed to high heat sources or an open flame, so don't hold a flame to it, and don't use it as, or around, a candle holder. Once fully cured, UltraClear Bar & Table Top Epoxy handles temperatures up to approximately 135°F: a hot coffee mug won't leave a mark, but anything straight off the stove needs a trivet.

The Safety Data Sheets for all UltraClear epoxy products are available here: https://ultraclear.helpscoutdocs.com/article/18-epoxy-msds