I found this bug on the feedback website and tested out as well.
Original post: https://feedback.minecraft.net/forums/578101-minecraft-bedrock/suggestions/32978602-%EC%9C%88%EB%8F%84%EC%9A%B0-10-%EB%B2%A0%EB%93%9C%EB%9D%BD-%EC%97%90%EB%94%94%EC%85%98-%ED%95%9C%EA%B5%AD%EC%96%B4-%EC%B1%84%ED%8C%85%EC%98%A4%EB%A5%98#comments
The Bug
When you look at the photo provided in the OP, the person who posted this bug tried to type this.
채팅이 이상합니다...
However, due to this bug, the result came out like this.
ㅊ챝채티팅팅ㅇ이이 ㅇ이잇이사상상ㅎ하합합ㄴ니닏니다다...
As you can see, the characters have been registered 2~4 times, making it nearly impossible to type in Korean. It seems like the game is trying to add a character every single tick.
Linked issues
is duplicated by 6
relates to 2
Comments 2
Cleaning up old tickets: This ticket had been set to 'awaiting response', but has not received a response from the reporter (~3 months+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines which includes steps to reproduce the problem.
Quick Links:
📓 Issue Guidelines – 💬 Mojang Support – 📧 Suggestions – 📖 Minecraft Wiki
Does this still affect the latest version? If so, please reply.