There are tons of interview mistake I see people make. One I can actually remember making was forgetting to turn off my phone before job interviews. It can actually be embarrassing.

However, I reached out recently to some HR professionals and asked them what job interview mistakes they see most job seekers making.

Below is the summary:

Top Job Interview Mistakes Job Seekers Are Making According to 20 Practicing HR professional

Not taking the interview seriously
Improper Dressing and Attire
Lack of preparation
Lack of two- or three-minute answers to fundamental interview questions
Talking about yourself and about your expertise without the context of the job you are applying for.
Lack of skills, knowledge, and experience required for the role
Not bringing a resume and assuming they have one printed
Going into the interview cold.
Lack of Confidence
Speaking too quickly instead of taking time to think their answer through
Not reading the Job Description properly
A actually treat the interview like a first date!
They don't do their research on the company


Here is the full article if you want to read more https://www.myjobmag.com/blog/745/12-hr-experts-share-costly-job-interview-mistakes-to-avoid