How to avoid over use of "I" in papers?
It's generally accepted to use passive voice in scientific papers. This would turn the cited paragraph into:

For the health belief model, four specific points were discovered
(taken into consideration?): perceived susceptibility, perceived severity, perceived benefits and perceived barriers. It was noticed
people aren’t very open when talking about covid, so the questions
were asked in the following manner. First, they were requested to rate the
severity of each point from 1 to 5. After they answered all the
questions, they were asked for justification of their replies. This
way ensures that respondents are more truthful.

Additionally, to avoid repetitive use of the same words, I highly recommend to look for synonyms in a thesaurus. There are also programmes that check English grammar in a text, perhaps it's also a good option for you.