Several of my add-ons have now been reported to have caused issues on realms, in that they enable other features that aren't coded into the addons.

Summary
Three of my addons, all with different UUIDs are enabling functions from someone elses addon when they're installed on some realms.
I've not been able to replicate this on my own realm, but comments are linked below from users encountering the issue.

Example:
My One Player Sleep pack, which only affects the player entity, has been reported to enable the custom crafting recipes of spawn eggs, mob spawner cages and end portal blocks when installed on a realm.

One Player Sleep Pack Contents:
📜Instructions.txt (Readme)
📜manifest.json
📜pack_icon.png
📁animation_controllers
➡📜fsm_ops.json (Makes night pass when player is sleeping)
📁entities
➡📜player.json (Links to animation controller)
📁functions
➡📜fsm_loop_ops.mcfunction (Advances Time)
➡📜fsm_start_ops.mcfunction (Triggers System)
➡📜fsm_stop_ops.mcfunction (Stops System)

As you can see, there are NO custom recipes in this pack.
UUID for reference: 120cd1ef-749f-430a-a0cb-5cb12388bf1c

The pack does not include any custom recipes but is still enabling them on the realm some how.

It's been reported that changing the UUID helps, however the pack has a completely unique UUID that I generated when creating this pack.

Comments on my YouTube videos started about a week or so ago (Early July 2020) about this but then in the last few days, I've been getting similar comments about two completely different packs that have two completely unique UUIDs.

My Mob Heads 2.5 pack and the Custom Armor Stands pack by DanRobzProbz are also now enabling these exact same custom crafting features on some realms.
The crazy thing here is each pack has a different UUID, yet they're enabling the same custom recipes.

Armor Stands UUID: 37b7ad97-6a83-4cc9-b5cb-e71673ab3087
Mob Heads 2.5 UUID: 050d4123-fe3f-4483-b30c-5fb43a4e4d68

Comments from my One Player Sleep Youtube Video:
1. Rayge Life • 4 days ago
Same here it added custom crafting recipes to my realm...

2. Axel SG • 4 days ago
Same here, I just realized after nearly a month...

3. Maranda Phillips • 3 days ago
If I add this pack to my realm it adds spawn eggs, elytra, nether stars, diamonds etc to the crafting menu but if I remove the pack none of that is there. None of my world settings changed. Odd.

4. Rayge Life • 3 days ago
FoxyNoTail not trying to be a bother dude. But I e tested it a few times and it is definitely coming from the pack. Is there a chance that the download link pack has been tampered with in some fashion? Perhaps the pack you made/have and are checking was altered somehow.

5. iPenguin42 • 2 days ago
There's something up with the pack, when I add it to my realm there are suddenly craftable spawn eggs, so I tried it on a testing world and no such problem.

6. Eric a.k.a. dlllCHAOSlllb • 1 day ago
I have this issue as well. We LOVED the way it works for our ops for our smp. However they find the Craftable eggs etc unacceptable most play on MCPE with a few on windows 10. Please help! You're the best!

7. Dahotdogman17 • 1 day ago
Same exact issue. I play Windows 10 on a realm with mobile and console players. I activate the pack and spawn eggs, saplings, Shulker Shells, even elytras are craftable. Hopefully this helps fix the issue.

8. Robo Cuber • 1 day ago
Ummm why can I craft spawn eggs, I didn’t really want that

Another realm owner sent me this video that shows the issue with a different pack:
My Awesome Kingg • 4 days ago
Hey I am having a problem. I don’t have any other add ons on my world but whenever I have this on it adds craftable spawn eggs and a bunch of other broken stuff that I don’t want.
https://youtu.be/Pcop5YSl1Yc

And then comments about the other two addons started to come in aswell...

A comment from one of the realm owners is as follows:
We discovered a problem with the Armor Stand add-on. that I feel you need to be aware of It is shared with a resource pack that allows spawn eggs to be crafted and dragon heads be used to craft monster cages. For the most part this is not an issue, but if any other realm on the same physical server installs the other resource pack, then the server will conflict with the UUID. Our realm was instantly enabled with the new resource pack because another realm installed it. I was able to fix it, by downloading our realm, installing the armor stand pack, after changing it's UUID, and everything worked again. Here is to hoping nobody took advantage of the crafting abilities before we caught it.

And one of my Discord Moderators sent me this message today about a third pack:
Spawn eggs, tridents and even elytra available for crafting. We were able to isolate the issue to MobHeads 2.0.5 I replaced the UUIDs and it seems to be working fine.