I'm no developer so I'm not entirely sure what this "Rich Hints Agent" extension is exactly, but I did find the extension's files here:
C:\Users<USER>\AppData\Roaming\Opera Software\Opera Stable\Extensions<randomcode>

It looks like it has 5 main files:

agent_event_source.js
event_registry.js
event_source_factory.js
main.js
tab_changed_event_source.js

plus a manifest file:
manifest.json

The code looks like a big jumble of functions and isn't really sorted (and not commented at all). it seems to be referring back to other things in possibly the core Opera code.

I moved these files out of the install folder, and when I opened up Opera again, I got a message saying that the extension is corrupted, and to go to the Extensions to repair it. The "Rich Hints Agent" is now shown as disabled with an "update" button to I guess install the new version, but other than the nag message, the regular tabs seem to load/work as expected.

The Aliexpress extension's permissions say that it only gets permissions to read data on the shoppingcart.aliexpress.com website, so that seems okay to me.

Who knows about the others...

I just want to say thank you and draw some attention to this - after updating to Opera 72, I see that the recently closed search (magnifying glass icon) now shows more than 3 recently closed tabs - and I'm happy about this Thank you Opera for restoring this functionality back even if it's not 100% of what it used to be (since it also includes this search and isn't a dropdown anymore).

I'm no developer so I'm not entirely sure what this "Rich Hints Agent" extension is exactly, but I did find the extension's files here:
C:\Users<USER>\AppData\Roaming\Opera Software\Opera Stable\Extensions<randomcode>

It looks like it has 5 main files:

agent_event_source.js
event_registry.js
event_source_factory.js
main.js
tab_changed_event_source.js

plus a manifest file:
manifest.json

The code looks like a big jumble of functions and isn't really sorted (and not commented at all). it seems to be referring back to other things in possibly the core Opera code.

I moved these files out of the install folder, and when I opened up Opera again, I got a message saying that the extension is corrupted, and to go to the Extensions to repair it. The "Rich Hints Agent" is now shown as disabled with an "update" button to I guess install the new version, but other than the nag message, the regular tabs seem to load/work as expected.

The Aliexpress extension's permissions say that it only gets permissions to read data on the shoppingcart.aliexpress.com website, so that seems okay to me.

Who knows about the others...