Because the 5500105 part is the wrong part.
These are the Toyota vehicles RockAuto says are a fit for the 5500105:
View attachment 4053828
Note that the 2021 Land Cruiser is NOT one of the vehicles that part will fit.
And here are the vehicles that fit the 5500106 part:
View attachment 4053831
Note that your 2021 Land Cruiser is supported.
Just so the story is complete, let's start with the facts:
The Toyota OEM TPMS sensor part number for a 2021 LC200 is 42607-48010:
View attachment 4053832
If you don't want to buy directly from Toyota, the equivalent from Denso is 550-0106:
View attachment 4053837
That same Denso part from RockAuto:
View attachment 4053838
Note the helpful install info at the bottom which explains about the OEM equivalent is a "RELEARN" type sensor.
What I don't know, and I hope others who have purchased the Denso sensor can chime in with more info, is whether you would also have to purchase a "fit Kit" for the sensors:
View attachment 4053844
It appears to me that the sensor direct from Toyota comes with these extra bits, but they are not shown in the pics from Denso.
HTH