I've been having the same issue for about 7 days now myself.
after checking this post everyday since and getting fed up with getting no response from Mojang I had a play around to see if i could find a work around.
After joining the realm, like most others I was disconnected after around 30secs. Restoring the world to a previous save didn't work, as did any other suggestions.
However, after copying the realm save and playing it locally for a day or 2 (realm crashed in the middle of mass breeding villagers) I've just replaced the realm with the updated 'Copy' and that appears to have fixed the issue. Currently been AFK on the realm for about an hour without being disconnected. Also able to use crafting tables, place blocks, trade villagers etc etc.
Is anyone else able to do the same to see if this works for them also? (I'm on an XBOX 1 S, not series S/X)
i'll also keep updating should any more issues come up
WORK AROUND / TEMPORARY FIX
Download the Realm to your device (Xbox, switch etc)
Play for 15 - 30 mins,
Save and exit
Upload world back to realm,
Play on realm for 1m-2min
save and exit realm.
Did this and it's been working as normal since.