After updating SonarQube from 8.0.0 to 8.9.3 the value of "Estimated after merge" changed and Quality Gate failed

Hi, team!

I’ve come across a problem after updating SonarQube from 8.0.0 to 8.9.3. Before the update the “Estimated After Merge” value of coverage of the Pull Requests had been about 70%, and after the update it dropped abruptly to about 44% (i.e., any scans that were performed after the update show 44%, whereas the scans prior to the update show 70), although the PRs were really small in terms of number of lines compared to the overal codebase. The overall coverage in the Develop (main) branch was still showing 70%. After an actual merge of one of the PRs, the overall coverage in the Develop branch dropped to 44% as well.

Could you give a tip what is a reason of this issue please?

SonarQube 8.9.3 Community Edition
The project runs in AzureDevOps
SonarScanner 5.0.0

Please find attached screenshots of QG

Successful analyze before updating:

Failed analyze after updating:

After Merge to main branch: