Laravel receives new requests with "Symfony" user agent every 3 seconds

Hi, I needed to log something in the boot method in one of my service providers and noticed that Laravel keeps logging the information every 3 seconds even after the initial request is done. Turns out, that it keeps getting requests with the "Symfony" user agent.

Request headers:

Accept:          text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Charset:  ISO-8859-1,utf-8;q=0.7,*;q=0.7
Accept-Language: en-us,en;q=0.5
Host:            localhost
User-Agent:      Symfony

This is happening with artisan serve on localhost, I haven't been able to test if the same is happening once deployed.

Is this behavior expected?