FIRST added a check on the HTTP Referer header around the time that divisions came out, preventing direct access to event team lists unless linked there from the FIRST website itself. This was presumably to save their server from the deluge of traffic from the various "are divisions out yet" scrapers.
I have a workaround that makes FRCLinks still work, but unfortunately Excel will keep running into that HTTP Referer issue, since it tries to access the data directly at that
https://my.usfirst.org URL that FRCLinks redirects to.