Integrating a Jitsi bot into the channel solves this.
> Good text chat (images, code snippets, emojis, reactions, etc)
All possible with good old web linking. Link to an image host, a pastebin, or a file host of your choice. Many IRC clients support inline display of image/media URLs.
All major IRC clients and servers support UTF-8 as well, so emoji away.
> Streaming Video (!!)
Jitsi (with a bot) or web linking.
> File share
Web linking.
> Robust bot integration
Quite possibly one of the strongest arguments for IRC. The protocol is well-documented, and it's very easy to write an IRC bot.
> Lack of security problem unlike the self-hosted alternatives have.
Also lack of transparency. The self-hosted open alternatives are auditable and can be inspected. Nobody knows what Discord does with user data or what security issues exist.
> Push2Talk - this is also important, I dont understand how e.g Teams dont have this shit.
Your (possibly self-hosted) Jitsi instance already has this.
> One account between all servers with ability to customize your identity
Until you get banned/blocked for some arbitrary reason, at which point you might as well start over, since everything is gone.
tl;dr: Web linking + some bot integration and client affordances solve all these. This is how the web is supposed to work.