Sonar PR Analysis not catching issues before merge to master

Hi, we are currently using SonarQube Enterprise Edition 9.1 and we have setup pull request analysis in our ci-cd pipeline. We have a constraint to merge the PRs into master only if quality gate passes on the PR analysis in Sonarqube.
With this in place, we are still seeing that there are some issues which are raised on master due to that commit though they were not caught during the PR Analysis. Any ideas on why this is happening so? PFA of screenshots of issues reported in the PR analysis and the ones on master.

Hey there.

It looks like your PR analysis has 3 warnings. What are they?

Hi, attaching them here-