Google Pixel 7a will not pair or stay connected over Bluetooth

The checks in more detail

Charge the accessory, because a weak battery gives weak signal and strange behavior, and keep it within a few meters without a wall between you. Google's Bluetooth help page recommends these steps in this order, and they solve most problems. For a car or a speaker with several profiles, open the gear menu for the device and make sure Phone audio, Media audio and Contact sharing are each as you want them. Delete the phone from the car's list too and pair again. If audio is poor, check that the phone is not also connected to another device that grabbed the stream,

and look at Developer options for a Bluetooth audio codec set to something the accessory does not like; resetting it to the system default helps. Interference from a crowded 2.4 GHz band, a USB-C hub near the phone or a wireless charger can break the link, so test away from them. Keep the phone updated, since Google fixes Bluetooth bugs in monthly patches. As a last step, use Settings, System, Reset options and reset Wi-Fi, mobile and Bluetooth, then pair again. If a device fails on every phone, it is faulty. If every device fails only here, ask Google for service.

Think about where the phone sits when the link breaks. A phone in a back pocket sends the signal through the body to earbuds in the ears, and the Pixel 7a's antenna is better at close, line-of-sight links than a link through a torso. Keeping it in a front pocket or a bag on the same side often stops cut-outs on walks. Also note the battery saver setting: an aggressive saver can pause background Bluetooth connections, so exclude your Bluetooth apps from battery optimization in Settings, Apps, if a smartwatch or tracker drops when the screen is off.