What happens when access to the Ethereal or Astral planes is blocked?

[Yora]

I know 3rd edition had all kinds of rules for which spells require the ethereal and astral (and shadow) planes to work. Is there anything similar in 5th edition? Aside from obvious cases like leomunds secret chest requiring an ethereal plane to store a chest on the ethereal plane, are there other spells, magic items, and creatures, that would be affected by this?

[Spriteless]

Are you asking as a player or a GM?

If a player, talk with your DM. It is especially in veresimiltude if you take the appropriate skill, probably arcana, a background or contact that can help research, and bring it up as a concrete problem that your character would like to spend downtime on. That's the sort of world building that high level PCs are supposed to participate in, imho.

If you are a DM, there's not a lot of guidance on magical theory. Just raw magic >> weave >> casters, which to my mind is just Mordenkainen's theory, the Dragons have their own, as do the devils, and celestials, and genies. 3e or pathfinder are sources you could use, if you want a robust simulationist system. You could also go the route of x-men cartoons. There is no mention of where Nightcrawler is between teleports, until it results in an interesting story.

[Tanarii]

On top of anything referencing ethereal ness or astralness not working:

Clerics lose their powers, or at least some portion of them that depend on Deities. Some/many Paladins too.

Any spell that involves summoning a outer planar creature would also fail. Conjuration summoning local spirits would still work though,

Many elemental spells would cease to work. Definitely the elemental conjuring ones. Then you'd probably have to go through every evocation and conjuration spell and decide which are bringing the power from the elemental planes, and which are brining it from somewhere on the prime material.

Healing spells and reversed versions would stop working, since there is no positive or negative energy to be accessed.

That's off the top of my head.