As someone who enjoys playing hardcore characters on some of the more challenging seeds, the poison trapped chest mechanic removes a core aspect of the game from the beginning of most new players runs: aka Splunking for treasure. Unless you have honey (in the jungle), the nurse (also need money), or just a ton of health, it instantly ends a hardcore run. While I get that you can just not loot until you find 10 hearts, or until the nurse arrives, you're essentially limiting a player by saying "ignore the core aspect of our game until x point." Every other trap in the game has an indicator or a warning: boulders, dynamite, darts. Poisoned chests are just annoyingly random. My suggestion would just be remove the trap from the 'surface' layer chests so that at least a player is able to get basic gear. Or on the other hand, provide the player an indicator that the trap is present like all the other traps in the game. My suggestion for that would be a faint green puff of smoke every so often to show there's a gas trap in the chest.