All of this Cleaners, anti-viruses etc. are too stupid and not reliable as for me. When I have any troubles I'm using system restore point backup.
Check some old Opera version (before this trouble appears) and see how it goes.

@Niseandryt

@Niseandryt said in Opera uses a lot of disk:

I've had this problem for a few weeks ago that System uses 100% disk every time I startup my computer, and doing some research I found that Opera is the one who makes that issue because uses the most quantity of I/O read I/O write I/O read bytes I/O write bytes
different processes of Opera uses a lot of each one of those
I/O Read 354,000 and still going up I/O write 318,000 and still going up I/O read bytes 480,000 and still going up really fast I/O write bytes 469,000 and still going up too
the 100% disk usage last for 2 minutes or so and thereafter drops back to 0 but it's annoying and I wanna know if this problem may be caused by Opera

Take a look here https://answers.microsoft.com/en-us/windows/forum/all/disk-usage-spikes-to-100-when-using-browser/35411ffe-8c46-4622-b1af-337b4c2731f8 for a similar topic