can you explain what these parameters are

Read here: https://developers.google.com/web/updates/2018/10/wasm-threads

and why they were enabled if this leads to a vulnerability?

Most likely unintended coincidence - performance versus security, as it often is.
If Chrome is not affected, then you should report a bug to Opera. If Chrome (Chromium) is affected too, then better report to Chrome (Chromium).

Well, before reporting check latest developer build - it is possible that this problem is already fixed. In my just updated dev version (70.0.3693.0) two checks (2 of 2) did report "not vulnerable"

Maybe the test itself is not stable. And my processors can't be called as 'modern' like it is said in the blog post's explanation.

The vulnerability itself is not 'stable'
Code in test script is a bit over my understanding, but it could be unstable either.

To read protected memory areas CPU cache is cleared, code is tricked to execute speculative read from protected area (which is discarded and thus not giving error - but data is already loaded into cache) and then some other memory addresses are read - read timing depends on cache containig specific data. Some information can be leaked even using somewhat random timing - I think this is exactly what you experience.

Maybe the test itself is not stable. And my processors can't be called as 'modern' like it is said in the blog post's explanation.

opera://flags/#enable-webassembly-threads

I disabled it, but in my case the result is still random (Portable 68.0.3618.104)

I have not heard about (widespread) real-word exploits, based on spectre (or meltdown). I would think such kind of vulnerabilites can be used for targeted attaks, where every bit of information can be valuable; for generic attakcs (to take PC over) this is a bit hard and unpredictable to use - of course I may be wrong here.

Did you check with a clean profile?

if you delete all the settings, it will be very bad and I will need to configure a lot from the beginning

@donq said in & Spectre the last Opera 68.0.3618.104 vulnerability:

What offline scanner says? https://www.grc.com/inspectre.htm

Meltdown & Spectre - NO!, NO! updates strongly slow down the system, I do not want to put them, I have hope for the browser itself.

@leocg said in & Spectre the last Opera 68.0.3618.104 vulnerability:

What about other Chromium based browsers?

not used by others Chromium based browsers. I only use Mozilla - everything is fine in it, there is no vulnerability.

any other sites to check for vulnerabilities?

68.0.3618.104
random result (when I click 'recheck'), sometimes it checks only few caches (8, 16, 32), sometimes checks all caches until 128. When it includes all caches including 128 it shows NOT vulnerable. if less caches were checked, then it shows vulnerable. Win 8.1 3rd gen core i3.