When trying to load into a world in certain conditions, the game gets stuck at "Loading Resources" and will never load afterwards. This was a bug I originally dealt with a while back on my iPhone 6s before I got an iPhone 11, but it's back again. There isn't a 100% way I found to replicate it other than just chance, as it happens around 50% of the time. I first noticed it again when loading into a "Caves and Cliffs" experimental active world, but it doesn't act the same as the first time. The render distance I keep my phones settings at is 20 chunks, and it's able to reach 36 maximum, but to get it to load every time without this happening, I half to drop it to 8 in settings. After the world loads or if it doesn't do this glitch, it runs on 20 chunks fine when putting the render distance back up, other than small bits of lag from the experimental stuff still a work in progress. When on my iPhone 6s before I switched and this was a problem, I had to either leave the app without closing it to have the game reload bar to move after 30 seconds or so to cause it to finish, or shut off any and all communication things including being logged into Xbox Live and being on airplane mode. I already tested it again and these things and the render distance drop all still work to get around it.

By the fact that this glitch seems to be unknown, I have a feeling it's linked to cellular data not being connected to the Minecraft servers when trying to set up internet multiplayer (Even in worlds with it shut off) and possibly with it linked to cellular connection to phone service, or the amount of chunks loading causing to to take longer, even though that was never an issue with the first few experimental world settings options and in basic worlds without the experimental active currently. I'm mostly addressing this now as back then I didn't have an account for this at the time and it never came to mind to upload this specific bug/glitch/issue, but I thought it was over when it stopped happening after upgrading phones, so now I know it wasn't just that specific phone since it was an old phone.

Update: As of 1.17.41 where they fixed the bug related to data leakage causing issues, this has become a bit more stable even in new worlds. It does still seem like depending on your settings, render distance, and the signal strength the phone is getting. It is a lot more stable when it comes to loading chunks though, that seems to be less of an issue with the bug now.

11/18/2021: Slight update. Found out it reacts to two other things that might lead to the source? It happens if I load into the game and start a world to load up with the experimentals on within the first few seconds or so after it shows I've connected to my account and it loads up my skin. The simple solution is just wait a few more seconds to make sure, but it also can't work still. It seems to happen more even if waiting longer depending on the signal I have. The only guess I have to what might be the main issue causing this is the app loads up too fast for the phone to load/ connect to the online servers and breaks when trying to load background account data while loading a world at the same time that has a lot of chunks to render in at the same time. If this is the case, not sure whether it counts as a bug, or just a connection issue that may not have been fully looked over on cellular data somehow, as cellular data seems to be a bit touchy when it comes to online things like hosting/connecting to others worlds lately. 

One other thing I found out about half an hour later of this. Turns out it also happens to experimental worlds on Switch with a weak internet signal from cellular data.

11/24/21 - After remembering about this while at a place with Wifi, I tested this to see if it was just the phone, or cellular. After loading up the same world(with experimentals active), including doing so as soon as the title screen loaded up, it loaded instantly after the world generating screen finished every time. Five minutes later after going away from the signal and attempting again with cellular, it got stuck first try. So there's a decent chance, it's either a cellular bug, how the game loads background data if you have a world with extreme generation where you load into, or both.