When pressing and holding Tab for about half a second, no one would be visible, including players. My version is 1.20.1, and the forge is 47.3.12

Those are sad words😭😭😭
If every entity gets one, may I find the one with that uuid? Sorry I don't know how to do and the erroneous entity may have been deleted so it may remain a secret forever

I think I have found the reason. I updated EntityCulling and deleted Easy Npc mod, because '1a35f834-20dd-400b-8a38-6d858a1c969e' looks like a file name in my playerdata folder. There was something still strange: no file had the name, and I had added the NPCs before, but now they all were killed so there should be no NPC left in my world. At least the issue has been solved
Thank you for your patience in waiting and for indulging my willful requests once again

That's the entity uuid, every entity gets one, so it doesn't help pin down which mod it is.

Uhhh what does the tab list have to do with entityculling?

Sorry for not expressing it clearly. I mean Tab key on the keyboard, not the tab list. When pressing it for about half a second, every entity becomes invisible. The problem never happened before adding the mod so I think pressing Tab key caused it to occur

This mod only has 2 debug keys that are not bound by default, so it doesn't listen to tab. Please re-try with and without EntityCulling, but it sounds highly unlikely that the 2 things are related.

It seemed even more strange. The problem only happened on my old game save. I must reopen my launcher to make everything correct because switching saves can't offer any help

Send the full latest log after it happens, I'll check if there is anything sticking out in there.

Thank you for your patience in waiting and for indulging my willful requests.
abbccc.txt
at about 01:47:24 I loaded my save

God there is a ton of errors in that log. At the end the renderstate is corrupted

[01:47:39] [Render thread/ERROR] [ne.mi.ev.EventBus/EVENTBUS]: Exception caught during firing event: Rendering entity in world

[01:47:38] [Render thread/ERROR] [ne.mi.ev.EventBus/EVENTBUS]: Exception caught during firing event: Already building!

[01:47:38] [Render thread/ERROR] [xa.hu.mi.MinimapLogs/]: Exception when calling the full entity renderer for 1a35f834-20dd-400b-8a38-6d858a1c969e before prerendering the icon.
java.lang.IllegalStateException: Already building!

Thats probably what is causing everything to not render properly. But you have so many mods in there, god knows what is causing that. EntityCulling just skips entity rendering, so can't think of a way that this would cause the entire rendering to get corrupted.
One idea: holding tab afaik shows the entity faces on Xaeros Minimap, and there are errors of it trying to render these faces. So my best guess is that some entity is broken due to some mod issues, and when you press tab it tries to render the face for the minimap and bugs out everything.

As I mentioned, there are literally hundreds or thousands of errors in the log you sent, kinda amazing the game works at all 😅. That uuid was just from one error, there are many and they are different. So the minimap icon render being the first trigger is just a guess.