checkstyle report calculator show difference between identical builds

have started two builds after each other. The source and build configuration has not changed yet checksytle reported changes in the issues.

first build reported:

Checkstyle: 72,184 warnings in 37 Checkstyle files.

• 72,184 new warnings

Second build reported:
Checkstyle: 72,184 warnings in 37 Checkstyle files.

• 243 new warnings
• 196 fixed warnings

third build
Checkstyle: 72,184 warnings in 37 Checkstyle files.

• 255 new warnings
• 197 fixed warnings
  4. build:
  Checkstyle: 72,184 warnings in 37 Checkstyle files.

• 170 new warnings
• 193 fixed warnings

Maybe it is related to JENKINS-2968 & JENKINS-5341 ?