If you ever used Google Account + Google Fi as carrier + stock Pixel factory OS image and later deleted Google Account + switched to GrapheneOS + switched to another carrier, then some of your inactive Google Fi eSIM information can still remain on your phone. Android (stock Pixel OS and/or GrapheneOS) cannot detect and/or wipe inactive Google Fi eSIM information with "Erase downloaded SIMs" in "Reset Options" menu.
On GrapheneOS, you specifically need sanboxed Google Play Services + active Privileged eSIM Management to detect any inactive Google Fi eSIMs still present on your phone. After activating Privileged eSIM Management, you need to use "SIMs" or "+" located right above "Privileged eSIM Management" setting to see if Google Fi eSIM is present.
This affected those who only used Google Fi physical SIM, but downloaded Google Fi eSIM and kept it in inactive state. Generally speaking, if you installed GrapheneOS on Pixel phones that were ever used with Google Fi in the past (or if you purchased used/second-hand Pixel phones) and have no need for Google Play Services, then it is a good idea to check for Google Fi eSIM leftovers by going through the process I described above.