Reliability Bugs on same Source code which had no issues 4 days ago

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Gitlab
sonar-scanner-cli-4.7.0.2747-linux
Dotnet

we are getting Reliability Bugs on Source code which had no issues 4 days ago. Same code while running Sonar scan getting the issue.
we have a Private Subscription with sonarcloud.io

Any update or rule change recently from Sonar cloud to check any new Bugs? Would like some details pls

Hey there/

Can you tell us on what Rules and what language the issues are being raised on?