It is clear that the problem
It is clear that the problem is caused by swelling or deformation of the rubber impeller in the pump.
Now it is well-known that Ethanol content in fuel can damage rubber parts. In this case, the Denso pump or portions thereof are made in China; unfortunately, many Chinese rubber & paint coating products we see in North American products are inferior and prone to early failure in many applications - unlike German or American made chemistry-based materials.
Clearly, Toyota is at fault for allowing this to happen in such an important component. The problem could be avoided by using higher quality materials.
I surely hope that Toyota Corporate figures this fact out certainly by Feb. 2021 and get this important fuel pump safety recall problem solved once and for all permanently.