yahoo has not provided free stock information since about the winter of 2018.
The following are from the old App Inventor forum and explain what happened.
https://groups.google.com/g/mitappinventortest/c/2N_j1exzQi4/m/jyLVt25UAwAJ
https://groups.google.com/g/mitappinventortest/c/xQHKr2sZgaw/m/SO4JmkzSBgAJ