In march 2022 (version 1.66), how to set terminal.findMatch？

Those are not standalone settings, they are colorCustomizations and are set in the settings colorCustomizations (settings.json) like so:

"workbench.colorCustomizations": {
    
    "terminal.findMatchBorder": "#ff0000",

       // you should get intellisense below for more findMatch color properties you can set
    "terminal.findMatch.......
}