It seems like a google issue: https://support.google.com/docs/thread/121088347/retrieving-data-from-sheets-results-in-404-error-50-of-the-time

feeds is the older version of Sheets API and it's shut down. See Google's announcement here https://cloud.google.com/blog/products/g-suite/migrate-your-apps-use-latest-sheets-api

Try tu use this function to get values as json

function getJson(id,gid){
  var txt = UrlFetchApp.fetch(`https://docs.google.com/spreadsheets/d/${id}/gviz/tq?tqx=out:json&tq&gid=${gid}`).getContentText();
  var jsonString = txt.match(/(?<="table":).*(?=}\);)/g)[0]
  var json = JSON.parse(jsonString)
  return(json)
}

• with id of the spreadsheet and gid of your sheet (may be 0)
• note that first row is dedicated to labels, then rows[0] corresponds to row#2 and c[0] corresponds to column A
• if you want to retrieve B1 (column 2 row 1) : json.cols[1].label
• if you want to retrieve B2 (column 2 row 2) : json.rows[0].c[1].v