Roblox complies with COPPA so has to filter out inappropriate text (both toxictoxic language, information as well as information regarding contact details, impersonatingimpersonation, dating and many many others).
The filter has different settings based on the age (13-<13 or 13+) and other settings (e.g. chat with friends only, no chat, chat with everyone) of your profile and the profile ofwith whom you are discussingtalking, but the filter is known to be overprotective and block some normal messages.
You can check the Roblox community rules in the help center article Roblox Community Standards.
And if there are certain words / textstexts that you think should not be filtered, then please raise this issue with Roblox Support.