@ArnoWantsCookies123 on macOS or Windows?
Also, what specific version as shown at the URL opera://about or opera://version?
Does the crash still happen if you disable "Show popup with clipboard and recent downloads when uploading files" at the URL opera://settings/easyFiles and restart Opera?
Is there a crash logged at the URL opera://crashes?
If you open up a new tab, type:
data:text/html,<input type="file">in the address field, press enter, click "choose file" and pick a file, does Opera crash that way too?