Sendgrid puts `\u0000` between two characters "LÁ"

[H7KZ]

I just found out about this, first I thought that it is mistake on my side, but after a while of debugging I got to a point that it is really inside sendgrid SDK

I am exporting an HTML template (generated from react-mail PS: no the mistake is not here, I checked it - here are the characters in plain text) and then I pipe it into sendgrid, and as you would expect it escapes the "Á" but then, for whatever reason, it puts \u0000 "null" between the "L" and "Á" ... funny enough I put a space between those two characters and then it did NOT put null in between and rendered the whole email... so... I am confused as hell now

How to reproduce it? Well... I would need to send you the email template which I cannot so that's not great, but to more describe the bug:

It only happen with the name "Marek Kolář" on a specific positon in the rendered HTML, if I would move it by one space to left, it magically works. If I renamed the person to "Kolář Kolář" it works, "Mark Kolář" works, "Kolář" works... everything works except "Marek Kolář"

What the....