SharePoint Server 2019 Anonymous users sporadically prompted for credentials

Hello,

I'm having a weird behavior when accessing a public site with anonymous access on my SharePoint Server 2019 Farm. I sporadically get asked for my credentials to access the page and the times I don't get asked it just works as intended. I managed to find out that the times I get asked for credentials there's a cookie present with the name WSS_KeepSessionAuthenticated but I don't quite get why it's only showing up from time to time.

Do you have any idea why this could be happening?

Thank you.