Advanced graphics' card diagnostic tools for Linux? (especially framebuffer)

I’m looking for tools to diagnose my GPU which is currently showing signs or hardware failure.

So far I’ve tried capturing the graphical glitches with OBS to see what happens, however they won’t get captured. Also I’ve tried memtest_vulkan, however that one couldn’t catch anything either.

https://github.com/GpuZelenograd/memtest_vulkan v0.5.0 by GpuZelenograd
To finish testing use Ctrl+C

1: Bus=0x0E:00 DevId=0x73DF   12GB AMD Radeon RX 6700 XT (RADV NAVI22)
Standard 5-minute test of 1: Bus=0x0E:00 DevId=0x73DF   12GB AMD Radeon RX 6700 XT (RADV NAVI22)
      1 iteration. Passed  0.0562 seconds  written:    5.8GB 280.1GB/sec        checked:    8.6GB 241.7GB/sec
     20 iteration. Passed  1.0497 seconds  written:  109.2GB 289.2GB/sec        checked:  163.9GB 243.9GB/sec
    110 iteration. Passed  5.0384 seconds  written:  517.5GB 284.6GB/sec        checked:  776.2GB 241.1GB/sec
    653 iteration. Passed 30.0519 seconds  written: 3122.2GB 288.0GB/sec        checked: 4683.4GB 243.8GB/sec
   1194 iteration. Passed 30.0135 seconds  written: 3110.8GB 286.7GB/sec        checked: 4666.1GB 243.5GB/sec
   1738 iteration. Passed 30.0468 seconds  written: 3128.0GB 287.2GB/sec        checked: 4692.0GB 244.9GB/sec
   2282 iteration. Passed 30.0064 seconds  written: 3128.0GB 287.7GB/sec        checked: 4692.0GB 245.2GB/sec
   2826 iteration. Passed 30.0099 seconds  written: 3128.0GB 287.3GB/sec        checked: 4692.0GB 245.4GB/sec
   3370 iteration. Passed 30.0206 seconds  written: 3128.0GB 287.3GB/sec        checked: 4692.0GB 245.2GB/sec
   3915 iteration. Passed 30.0452 seconds  written: 3133.8GB 287.7GB/sec        checked: 4700.6GB 245.4GB/sec
   4461 iteration. Passed 30.0401 seconds  written: 3139.5GB 288.3GB/sec        checked: 4709.2GB 245.9GB/sec
   5007 iteration. Passed 30.0219 seconds  written: 3139.5GB 288.4GB/sec        checked: 4709.2GB 246.1GB/sec
Standard 5-minute test PASSed! Just press Ctrl+C unless you plan long test run.
Extended endless test started; testing more than 2 hours is usually unneeded
use Ctrl+C to stop it when you decide it's enough
^C
memtest_vulkan: no any errors, testing PASSed.
  press any key to continue...

I’d like to make sure it really is an unfixable issue before buying a new expensive card (after all this 6700 XT shouldn’t die this fast), however any tool I can find is always either Windows or Nvidia-only.

I suspect something with the framebuffer given the kind of bugs / graphical artifacts. Would love to show, but can’t yet upload nor link anything here. Said artifacts are getting more since 2 days, and very quickly.

Any recommendations?