Hi Yocaxx,
Welcome to Microsoft Community.
Based on your description, I‘ve tested it for you.
The test results are indeed as you mentioned, with a visual effect of one letter that stands out extra.
This was a very valuable find, and I found you the contact email provided by the team.
- ******@swiftkeyapp.zendesk.com
You can report this phenomenon to the appropriate software team.
Your valuable input will help the development team investigate and optimize the problem.
If there is anything not clear, please do not hesitate to let me know.
Best Regards,
Kyo - MSFT | Microsoft Community Support Specialist