Verizon Executive Relations team reached out to their network team and the finding is that Tencent is not announcing the prefixes to them.

Result: Verizon is not going to pursue this.

On Wed, Jul 21, 2021 at 12:11 PM Stephane Bortzmeyer <bortzmeyer@nic.fr> wrote:

On Wed, Jul 21, 2021 at 11:35:35AM -0400,
S Umple <sumple@gmail.com> wrote
a message of 61 lines which said:

> <VZ INET router>#
> 81.0.0.0/8 is variably subnetted, 2835 subnets, 14 masks
> 121.51.0.0/16 <empty>
> 182.254.0.0/16 is variably subnetted, 3 subnets, 2 masks
>
>
> route-views.routeviews.org>
> 81.0.0.0/8 is variably subnetted, 3247 subnets, 19 masks
> 121.0.0.0/8 is variably subnetted, 2571 subnets, 18 masks
> 182.254.0.0/16 is variably subnetted, 113 subnets, 5 masks
>
> Anyone able to validate my findings, and/or take this issue to higher VZ
> support?

Testing with the RIPE Atlas probes show that 121.51.0.13 (which is
pingable) is not reachable at all from AS 701. But it still has
reachability problems from other networks in the world, with many
timeouts (but the problem at 701 is more radical).

At least 121.51.0.0/16 and 121.51.0.0/23 seems to be seen in many
places.