“Another possibility to keep in mind is that lead becomes gaseous at low temperatures, and would be gaseous in magma if it were not for the extreme pressures deep in the earth. It also becomes very mobile when hot. These processes could influence the distribution of lead in magma chambers…”
“…Here is yet another mechanism that can cause trouble for radiometric dating: As lava rises through the crust, it will heat up surrounding rock. Lead has a low melting point, so it will melt early and enter the magma. This will cause an apparent large age. Uranium has a much higher melting point. It will enter later, probably due to melting of materials in which it is embedded. This will tend to lower the ages.”
Read more about the details here: http://www.cs.unc.edu/~plaisted/ce/dating2.html
Picture from: https://pixabay.com/photos/the-periodic-table-chemistry-4273681/ accessed 1/6/23.