I'm running M2.3.5. Every so often I'll get a small batch of errors from IPs outside my country (all US). I'm getting notifications in the form of Store Debug Errors. Here's an example:
Server cannot match any of the given Accept HTTP header media type(s) from the request: "text/html" with media types from the config of response renderer
I even found someone else who ran into this on the M2 Forum. I don't see a reason why anyone would be trying to access rest in this way other than maybe someone is poking around? Especially as the source is outside our catchment country.