Comment 15 for bug 1825497

It's generally not a good idea to disable any sandbox mechanism unless you really know what you're doing. See https://chromium.googlesource.com/chromium/src/+/HEAD/docs/linux_sandboxing.md#the-sandbox-1 for more information on the seccomp BPF sandbox.

There are other mechanisms, but they don't replace seccomp, they work in conjunction with it.

If you really need to use flash and can't wait for a fix to be published, I'd recommend using firefox to access that specific site, it's not affected by the bug.

Note that a fix is being worked on upstream, and it will be backported to Ubuntu as soon as possible.