yeah sure but the breathable surface area of the jar is miniscule in comparison to its volume also CO2 is heavier than air so every pore in that mycelium block is full of CO2 and it can’t go anywhere and humidity doesn’t matter if the thing can’t breath

I’m not a grower myself but fungi need oxygen and produce CO2 iirc. So if you put them into glass jars with small openings on top, it might just saturate with CO2, which of course then kills the fungus. Just spitballing though.