I switched phones recently, and am very satisfied with my Xperia, but there’s this one useless icon in the taskbar that annoys me a bit and that is like to hide, but I can’t identify it, could someone help?

I tried SystemUI tuner, but it doesn’t list it as one you can blacklist in the list of toggles, and I don’t know how to find it’s key to add it as a custom one. Tried turning off calendar notifications, but that’s not it - it still shows. Does anyone know what it is and how to hide it? It’s a minor annoyance to be sure, but it’s completely useless, and I’d like it gone if possible. Thanks in advance for any help!