This is because according to a report from XDA Developers, they have uncovered more evidence to suggest that the Pixel 5 will instead be powered by the Qualcomm Snapdragon 765 (or one of its variants) instead. This is based on the latest strings of code discovered in the Android 11 Developer Preview by XDA Senior Member cstark27, in which there are references made that suggests that the phone could use the Snapdragon 765 chipset.
XDA aren’t alone in their claims as another separate report from Android Police’s David Ruddock also suggests that the Pixel 5 will be powered by the Snapdragon 765G chipset. It is unclear why Google is opting to use the less powerful Snapdragon 765G chipset, but it is possible that it might be related to costs.
The Pixel phones have been seeing a steady rise in its prices over the years, so by switching to a mid-range chipset, Google could be looking to lower the costs, which in turn could lower the price for consumers. Either way, take it with a grain of salt for now, but hopefully we’ll have more details in the near future.