"On 4th and 5th generation Pixels (which use a Qualcomm baseband providing cellular, Wi-Fi, Bluetooth and GNSS in separate sandboxes), almanacs are downloaded from https://qualcomm.psds.grapheneos.org/xtra3Mgrbeji.bin which is a cache of Qualcomm's data. Alternatively, the standard servers can be enabled in the Settings app which will use https://path1.xtracloud.net/xtra3Mgrbeji.bin, https://path2.xtracloud.net/xtra3Mgrbeji.bin and https://path3.xtracloud.net/xtra3Mgrbeji.bin. GrapheneOS improves the privacy of Qualcomm PSDS (XTRA) by removing the User-Agent header normally containing an SoC serial number (unique hardware identifier), random ID and information on the phone including manufacturer, brand and model. We also always fetch the most complete XTRA database variant (xtra3Mgrbeji.bin) instead of model/carrier/region dependent variants to avoid leaking a small amount of information based on the database variant.

Qualcomm Snapdragon SoC devices also fetch time via NTP for xtra-daemon instead of using potentially incorrect OS time. We use time.grapheneos.org when using the default GrapheneOS PSDS servers or the standard time.xtracloud.net when using Qualcomm's servers. Stock Pixel OS uses time.google.com but we follow Qualcomm's standard settings to match other devices and to avoid the incompatible leap second handling. These connections all go through the Owner VPN so it isn't a real world fingerprinting issue."

From: https://grapheneos.org/faq#default-connections