From a Jain Dharma perspective, there are a few key points about mushrooms:

• Ahimsa (non-violence) and living beings: Jain ethics aim to minimize harm to all life forms. Mushrooms are fungi and are considered living beings. Eating them involves harming or killing microscopic life, which many Jains prefer to avoid.
• Nature of fungi: Unlike plants, mushrooms do not have chlorophyll and grow by consuming organic matter. Some Jain authorities view fungi as more closely related to other living beings that are not suitable for ahimsa-based diets, so they avoid them.
• Karmic considerations: Jain practice emphasizes causing the least possible suffering and karmic bondage. Harvesting mushrooms can involve harming tiny organisms in the ecosystem, which some adherents see as undesirable.
• Practical and safety concerns: Many edible mushrooms require precise knowledge to distinguish between edible and poisonous varieties. Consuming misidentified mushrooms can cause serious harm, which is another reason some Jains choose to avoid them.
• Varietal views between Digambar and Shwetambar: There isn’t a single universal ruling across all Digambar and Shwetambar communities. Some may classify fungi as non-vegetarian or not suitable for strict ahimsa-based diets, while others might be more lenient. The emphasis, however, remains on minimizing harm and following a disciplined vegetarian lifestyle.

If you’d like, I can share concise references from Jain scriptures or explain how different Jain lineages discuss this topic in more detail.