It keeps having the same head even when someone else is typing it changes all the chat messages to their avatar

That's super weird, I can't really think of a reason why this would happen, except if you're using a really old version or so.

What Minecraft version and mod loader (Fabric, Forge, NeoForge) are you using?
Are you using any other mods, especially if they are chat related?

Other than that:
What is the name of that player? Is it something weird like a single [ or ?

When you click on any player's name or the "MVP", does it put /tell some_name in your chat box?

this has also happened to me i have realized that the head oh the last person in chat which is in your case "tcg_bubbles" repeats with the rest of the players

now if smn else texted in chat the chat will update and the last msg in the chat bar would be"jdaddyyy28" then that player's head would appear in every other person and so on

i have the same glitch and i use fabric and this glitch happens even in a private server and my friend has a normal name no spaces or wierd marks and i am on 1.21.5 when i was on 1.21.4 it was working fine mabye its related to that

now if smn else texted in chat the chat will update and the last msg in the chat bar would be"jdaddyyy28" then that player's head would appear in every other person and so on

Ohh, so it's always the last player's head that's being applied to every message.
I think that narrows this issue down to a chat refresh not working properly.
In vanilla, a chat refresh happens when the chat settings change or whenever a chat message is delayed (due to the Chat Delay setting).

However, I cannot reproduce the issue (in 1.21.5) no matter what I try, so I can only assume there's another mod involved.

So I am once again asking

apple skin
better F3
bobby
capes
wavey capes
continuity
enchanted block entites
fabric language kotlin
lithuim
resse's soduim mod
chat heads
cloth config api
mod menu
simple voice chat
shulkerbox tool tip
soduim
uku armor
xaero's world map
text placeholder API
i dont think any of them have any relation to chat tbh

Hm... those indeed don't look very chat related.

Only two thoughts so far:
The Capes mod is related to skins, which Chat Heads reads. (Though from quick testing, it doesn't seem to interfere.)
The head rendering could theoretically be infuenced by Sodium. (Seems very unlikely.)

Gonna test all of the mods tomorrow. (As far as I can with a single Minecraft account.)

Do you have any tips for how I could replicate the issue?
Does it always happen or does it randomly start happening?

If you want you can try disabling all other mods to see if the issue disappears, if not, we know it really is a bug in Chat Heads (for 1.21.5 at least).

the glitch always happens for me

i think it started as soon as i started playing 1.21.5 so maybe it is related to that since in 1.21.4 it was working fine(i made sure to put the mod in the latest version)

anyway i disabled all the other mods the glitch stayed there

anyway i disabled all the other mods the glitch stayed there

Hm... Are you by chance using a modded client like Feather Client or similar?

yea i use feather client its way easier to add mods there but i am pretty sure it isnt feather client since on 1.21.4(on feather client) the chat head mod work normal and nothing is wrong

Well, there's your problem.

This is not the first time Feather client (or other "clients" for that matter) caused issues with Chat Heads.

I can only repeat myself on that matter. Here's a link to an answer I gave back then:
#31 (comment)

In short:
Do not use any "clients".
Most, if not all, are known for their scummy practices like selling your data and stealing code from mod creators.
Their features add nothing a mod couldn't do.
They modify the game in ways we mod developers cannot account for (because everything is closed source), so you will run into issues just like this.

Instead, I highly recommend getting a good launcher like Prism Launcher or the Modrinth App.
They won't mess with your game, they won't steal your data and they allow you to very easily install and update mods as well.

P.S.
In case this issue happens without Feather client, let me know, so I can reopen the issue.
(Though I highly doubt that is the case, as the seen behavior indicates game modification.)