Redirected searches or redirected search result links can be caused by internal malware -- a bad add-on -- or by external malware that intercepts your connection to the web. Some support resources:
For detailed help, I suggest posting this problem on the Mozilla Support site. They have a team of support volunteers to troubleshoot malfunctions with your currently installed version of Firefox, while this site is focused on idea submissions for future versions of Firefox (looking ahead anywhere from 8 weeks to many months). Here's a link to the new question form (for Windows/Mac/Linux): https://mzl.la/3y1vQUQ
