You can see the table here: https://people.physics.anu.edu.au/~ecs103/chart/?ShowStable=...

When I click on the lead-208 box, it credits data from:

NUBASE2020: https://doi.org/10.1088/1674-1137/abddae AME2020: https://doi.org/10.1088/1674-1137/abddb0

It also only says that alpha decay is “possible”, not that it happens with any frequency—in fact, it lists Pb-208 as stable.