Can I redirect */?cat=-1

You will need to decide what is appropriate to do for your site based on the information you have in the logs and the purpose of your site.

Hello John,
I would like to redirect
*/?cat=-1
to a 410
is that possible ?
If so how?

Yes. Create your redirect and set the action to ‘error’, as described here:

https://redirection.me/support/redirect-actions/

The redirection is clear, I am unsure about the syntax for */?cat=-1
is it really that easy?

Is * part of the URL or are you trying to use a wildcard?

for example:
/de/page/22/?cat=-1
/it/page/33/?cat=-1
/page/24/?cat=-1
…
Can I redirect them all with one entry?

Details can be found here: https://redirection.me/support/redirect-regular-expressions/

thanks
Love it, here the answer
^\/(.*?)\/\?cat=-1