Unexpected, unredable characters in generated HTML

[UNOwen]

Describe the Bug

When rendering HTML using react-email 3.0.1, I randomly observe unprintable characters rendered in between or instead of the non-latin letters of the email text, no more than 1-2 occurrences per email typically. The issue seems semi-random, dependent on the amount of react markup and text before the affected character, and also dependent on the execution environment (locally rendered preview and server-side cloudflare worker insert these "broken" characters at different parts of the rendered HTML).

Example:

<Text className="text-zinc-600 dark:text-zinc-300 leading-6">
        Поздравляю! Вы завершили офлайн-курс по улучшению речи и литературному мастерству Litcondit. 
        Если вам понравились занятия и вы заинтересованы в том, чтобы научиться виртуозно говорить и писать, 
        а еще разбираться в литературе, приходите на занятия:
</Text>

Result:

Поздравляю! Вы завершили офлайн-курс по улучшению речи и литерату�рному мастерству Litcondit. 
Если вам понравились занятия и вы заинтересованы в том, чтобы научиться виртуозно говорить и писать, 
а еще разбираться в литературе, приходите на занятия:

(note the � character)

        "@react-email/components": "^0.0.24",
        "@react-email/preview": "0.0.11",
        "react-email": "3.0.1",

Which package is affected (leave empty if unsure)

react-email

Link to the code that reproduces this issue

https://github.com/UNOwen/litcondit-worker

To Reproduce

Have the below snippet repeated multiple times:

<Text className="text-zinc-600 dark:text-zinc-300 leading-6">
        Поздравляю! Вы завершили офлайн-курс по улучшению речи и литературному мастерству Litcondit. 
        Если вам понравились занятия и вы заинтересованы в том, чтобы научиться виртуозно говорить и писать, 
        а еще разбираться в литературе, приходите на занятия:
</Text>

Preview the dev version of emails or render in production. Observe broke characters in the email.

Expected Behavior

No unprintable characters in the email.

What's your node version? (if relevant)

No response

[blnvdanil]

We have also encountered this bug, it occures randomly, any change to the JSX layout or styles may lead to appearing/disappearing of these characters, it seems to be a \0 character

[gabrielmfern]

The code to the reproduction seems to be down, can you make it public?

[UNOwen]

The code to the reproduction seems to be down, can you make it public?

Gabriel, I’d like to keep the repository private, but I granted you access.

[UNOwen]

Upon some basic investigation, the character involved has hex byes of EF BF BD, and is the https://www.cogsci.ed.ac.uk/~richard/utf-8.cgi?input=%EF%BF%BD&mode=char "REPLACEMENT CHARACTER". It repeats twice in a row a lot of the time. It overwrites the contents of the email rather than inserting itself in between letters. E.g. hex bytes D0 BF for letter "п" were replaced with EF BF BD EF BF BD. The bytes replaced seem random. The replacing characters are always the same replacement character as far as I could reproduce.

[KevinGregull]

We see the same issue occuring. For us it happens on the "€" Character. I am quite certain that this is not an input encoding problem but rather something that occurs during the rendering of the HTML. Because we do display the € sign in Order Line-Items which are rendered in a loop. Sometimes a single of the looped € Characters is being replaced by the aformentioned �� characters, while the others render fine. It also happens with Umlauts sometimes "äöü". I've never seen it occur in any standard ASCII Character, thus far.