Classic widgets stopped working

I am not even aware of such a functionality? I don’t think it’s part of the Classic Widget plugin.

Did you perhaps use another plugin that has this function and which is now deactivated?

It is also possible that it was added by your commercial theme. In this case you would have to contact their support: https://www.themehorse.com/support-forum/ – questions about commercial products are not allowed here in the forum.

There is no such thing in the core. The Classic Widgets plugin only deactivates the block widgets and does not add any functions. Therefore, this must have come from some other plugin you are using or your theme.

The link looks like a part of Jetpack to me. If you have any questions, please contact their support forum: https://ww.wp.xz.cn/support/plugin/jetpack/