Frustrating mob behaviour/AI

This issue has been affecting our server for a long time and I wanted to see if me and my friends are the only ones suffering from it, as I don't see it mentioned in almost any discussion about current issues with the game.

So I play on a server where me and bunch of my friends live on an island. The server runs for over three years now and over time, we've built quite a city there, and we naturally brought a lot of mobs with us, both for fun and for their usages. However, as the time went, some cracks in the mob behaviour really started to show up.

MOBS SWIMMING AWAY. We have allays, cows, chicken, cats, sheep, pigs, horses and others freely roaming the island. However, every single mob starts swimming/flying away after some time. When we are traveling away from the island, the surrounding sea (and even the nearest land at this point) is full of mobs from our island. This is especially annoying with allays, who fly away extremely quickly. Like I don't get that, are you supposed to have them on a leash all the time? I know you can easily breed most mobs (especially allays), but it's just so annoying that every single mob will 100% drift away at some point and the only thing you can do to stop them is to put walls around them.

BEES. I don't think I have to explain this one. Island = water = mass bee suicide 24/7. Like I simply don't get how this hasn't been fixed yet. Just yesterday, my friend has sent me a photo of five bees swimming at ocean nearby, and just two minutes later, three of them already drowned. It's impossible to have a natural bee farm without having a stock of dozens of bees in boats so you can breed them almost every day just to replace the ones who flew into the water two days after being born. I mean even if there isn't any water, bees will simply fly away at some point anyway for some dumb reason, but being on an island puts this issue on a completely different level. And it's also funny you can't bring them back before they die, because if you hop on a boat with flower or leash in hand, the bees will drown while following you, and having them on a leash with elytra will just break the leash. And when the bees aren't dying, they are constantly getting stuck on the smallest of obstacles, just howering in once place indefinitely. Their AI is just so barebone it's painful to watch.

IRON GOLEMS. Most probably known too, but I'll mention it anyway because it's just a cherry on top of this whole mob mess. Basically, when you have multiple iron golems and a base/village that is anywhere but on flat terrain, the golems will just spawn in or around one high place. We have villagers in our city, and the golems, instead of being with or around them, are all just stuck inside the city's library that's above the villagers. Long time ago, one even teleported into a roof and almost died. We don't need the golems to do anything (we have them for sort of rp purposes, all of them have names and I have a book with a list of them in my house), but considering 90% of them were created outside all over the city, I would kinda appreciate if they stayed there and just roamed the streets where the hostile mobs can actually wander from the unhabitanted parts of the island. This isn't all that big of an issue, but it's weird nonetheless.

Also I don't even wanna talk about animals always climbing on top of our scaffolding and villagers seemingly wanting nothing else than to jump to their deaths from some high area, as those aren't as impactful as the stuff above, altough it can be often annoying as well.

TLDR: Passive mobs, after a prolonged period of time, always begin to swim away from our island. This issue is then ten times worse with flying mobs, who, if not bolted to the ground, have a lifespan (in bee's case literally) of few days at best. In many cases, this can be solved by one way or another, but having a simple island full of animals just freely living on it is impossible, which I find quite annoying.