Text area field content not accessible on certain translations when "embed media" enabled in formatter using CKEditor5

Thanks for the detailed report! 🙏👏

This needs a failing functional JS test to reproduce this problem.

One important question: can you also reproduce this without using translations? Asking because I really don't understand yet how translations can be a crucial part in reproducing this… 😅

I will try playing with the content. My guess is that maybe there's a special character in the Spanish translation, maybe even in the attribute of a media tag.

I'd be shocked if that turns out to be the root cause! 😅 Unicode shouldn't be a problem 😊 But … yeah … maybe we're using some str*() function that should be mb_str*()? 🤔

OK, it was the content, but it was unknown HTML tags (in the Spanish translation, it had <h3procesos></h3procesos> and <pla></pla> (the content was very long, so not easy to spot, especially because it didn't show any errors on the front-end). Not sure exactly what the relationship between this and "Embed media" options is, but I'm inclined to move this ticket to "Closed (works as designed)".

+1 — and this seems to be a duplicate of 🐛 [upstream] [GHS] CKEditor 5 does not retain custom HTML tags that are not defined by CKEditor 5 plugins whenever /.*/ is not allowed (e.g. when filter_html is enabled) Postponed given that apparently custom tags are being used.