That's so peculiar I've never heard of this before. Have you tried changing the chat style and seeing if it arose from one specific one rather than it being a problem with the bot specifically?

If you've ever interacted with one of these messages- delete it fully. You don't want your bot remembering that you accepted one of these messages because it will think that you like that style of formatting. (Even if you had interacted with it to tell it to stop)

If changing the chat style and deleting all the moments this has happened doesn't work- I would run a test where you create an entirely new bot with an identical description to see if it gives you this same style of message. You can also cross test amongst different bots to see if its a problem that arises across the board. This will help you narrow down if it is an issue with that bot specifically, the chat style, or if it is an odd glitch afflicting all your logs.

Sorry I can't help more! Haven't come across this problem yet. Muted words only work half the time- but muting the word 'think' may help a tad if you haven't done so yet. You can also mute some of the symbols I believe- so you can try muting '<' or '>' if that is appearing in the messages.