Opera GX came out with this new feature. I tried testing it on a fresh profile.

Attempting to click "Clean Now" results in an error in the console:

TypeError: Cannot read properties of undefined (reading 'erase')
    at Proxy.cleanNow (post_mortem_modal.js:48:38)
cleanNow @ post_mortem_modal.js:51

Opera details:

Version: LVL5 (core: 101.0.4843.74)
Update stream: Early Access
System: Windows 10 64-bit
Chromium version: 115.0.5790.171
UA: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/115.0.0.0 Safari/537.36 OPR/101.0.0.0 (Edition std-1)