That is RAW as it written in the description for the School of Necromancy at the back of the PHB.
I believe there is actually. For example it says "Divine Magic, as the name suggests, is the power of the gods, flowing from them into the world" they also specify "the ability to cast cleric spells relies on devotion and an intuitive sense of the diety's wishes".
This tells me that the magic flows from the gods, and that its use in spells is from the wishes of the god. And, since we have "unholy magic" then I would imagine that the deities can also grant "holy magic". This seems most connected to their alignment, in RAW.
Sinister gods of Evil and darkness still grant their clerics radiant spells, daylight, healing and the ability to conjure celestials.
That is just a factor of having a "one size fits all" cleric spell list with only limited customisation.
I look at it that clerics technically have the
option of casting spells that might conflict with their deity. Just as they have the option for being an alignment that might not fit so well. If there is any repercussions for a cleric acting against their deity, that is for the DM to adjudicate.
A Cleric of the Silver flame technically has access to the Animate Dead spell. However I can't imagine a true one ever using it. Its up to the player to pick spells to prepare that fit the character and concept of the cleric.
Ah, apologies, under Fungus I thought there was a mold. They have the Gas Spore and two types of mushroom though. Must have been the Violet Fungus that I was thinking of.
I think that they're considered environmental hazards or traps, and are in the DMG.
Vegepygmies from Volos might be what you're after?
I'm just imagining a retired warlock frequently using animate dead to work his farm.
That would work. As long as he is really careful about locking them up at night and putting up warning signs. I wouldn't regard casting Animate dead to reassert control over undead you had already created as an inherently evil act.