How to understand "Potentially dangerous Request.Path value detected"?

Question

ASP.NET

Hello!
Until yesterday, everything was fine, since yesterday it began to pour into the log every minute:
A potentially dangerous Request.Path value was detected, received from the client "<"
did not reveal that this was due to my edits, so I added to the web config: requestPathInvalidCharacters=""
now every minute error in logs: Potentially dangerous Request.Path value received from the client was detected (="...nts/05
I think maybe someone is trying to hack and set up the robot, adding that the IP address is saved along with the error. I see different IPs of other cities .. .. my site is purely regional... and how requests from other cities, even very distant ones, cause this error - I'll never know...
reason:
swears at the feed.mikle.com widget