Also apparent in 25w21a… I thought this was a rendering problem with my machine. Glad I checked here first!
Unsure if this also applies to OP's issue, but I also am unable to use \n as an escape character in 25w04a, which has lead to a multitude of my text functions in my datapack breaking.
I didn't see that this issue already exists in MC-272643, but I'm hoping it gets fixed regardless.
I think a good fix for this would be for the command to simply grant the player all advancements available, without any toasts or audio whatsoever.
If a player wanted to be granted every advancement (like you said), it's unlikely they're intending to read all of them as they come through.
Can confirm: the same issue occurs with consuming oversized milk buckets.
I think the issue can be easily replicated by trying to consume any oversized item that would normally give you another, such as stews.
I am also experiencing this bug. It goes back to 1.21.8 as well.