In regards to Persona skin support, we do technically still support them, they are just disabled on join, to improve performance for our players - if you switch to a Persona skin once you’ve joined the server, it should work normally.
The idea that we should jeopardise the performance and experience for a large number of players simply because some may consider their experience to be ‘already bad’ isn’t something that sits right with us - we want everyone to be able to enjoy the best experience possible!
As for the ‘pink glitch’, the issue is entirely out of our control, and is down to an issue with Minecraft’s rendering engine, RenderDragon. As much as I understand your frustrations here (it very much frustrates us too!), there is absolutely nothing that we haven’t already done to prevent it - believe me, we’ve tried!
Be sure to leave an upvote on the report on Minecraft’s official bug tracker if you’d like to see this fixed as much as we do! - https://bugs.mojang.com/browse/MCPE-105487
Lastly, you mentioned the skins from the Sonic DLC pack - most of the skins in the pack were originally flagged by our systems for being too big and unfair for gameplay, but, we granted an exemption for these skins for the duration of the Sonic event. The exemption for these skins was never technically removed, but the creators of the skin pack made some changes to it, which caused it to no longer be exempted (as the skins’ identifiers had changed)
We may consider adding an exemption for the updated skin pack, be sure to post a separate suggestion if this is something you’d like to see.