Is it safe to input your phone number in a not secure website?

Unfortunately my school makes me fill out a form through a website flagged as "not secure". This issue has only been made apparent this past year. Thankfully, the only personal information I input is my name along with my organization's email and my personal phone number.

Tech support hasn't been much help, as their advice is to mainly have me switch to another browser, which would not help. How safe is it to continue using the site, are there any …

email flagged information input issue name organization personal personal information phone phone number privacy safe school tech website