OpenCV version: 4.5.2-dev, Last reproduced: 2b787eb

The test fails time to time on several Linux based platforms, including PR test that are not relevant to the code:

• Ubuntu 18.04 x64: https://build.opencv.org.cn/job/precommit/job/ubuntu-18.04/555/ (The PR just tunes documentation). Test output:

/home/opencv-cn/slave/workspace/precommit/ubuntu-18.04/opencv/modules/gapi/test/gapi_fluid_test.cpp:903
Expected: (mem_before) >= (mem_after), actual: 150437 vs 150593

• Cross build for RISC-V + QEMU: https://build.opencv.org.cn/job/nightly-master/job/ubuntu-20.04-riscv64/54

/home/opencv-cn/slave/workspace/nightly-master/ubuntu-20.04-riscv64/opencv/modules/gapi/test/gapi_fluid_test.cpp:903
Expected: (mem_before) >= (mem_after), actual: 34105 vs 34167

System information (version)

• OpenCV => ❔
• Operating System / Platform => ❔
• Compiler => ❔

Detailed description

Steps to reproduce

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues,
  forum.opencv.org, Stack Overflow, etc and have not found solution
• I updated to latest OpenCV version and the issue is still there
• There is reproducer code and related data files: videos, images, onnx, etc