The UK is not part of the EU anymore.

Thats neither factually nor theoretically correct, as all the EU laws apply until the transition period has expired, which I wouldn't be surprised will be extended given corona has taken so much focus and time away from it.

Officially they are no longer part of the EU. They have agreed to abide by the rules of the EU for now, and the EU has agreed to allow them to trade as though they were part of the EU, but they officially left on Jan 31.

Duck typing says they're currently a member.

It's both factually and theoretically correct - the UK has left the EU, but laws are extended until the transition period is over.

Note the absence of the UK in the below sources:

https://www.gov.uk/eu-eea https://en.wikipedia.org/wiki/Member_state_of_the_European_U...

It is theoretically correct. The factuality is the point under dispute...

What's your definition of 'in the EU' and 'fact'?

If a nation state doesn't recognise itself being in the EU, and the EU doesn't recognise the nation state being in the EU, It's not in the EU.

https://europa.eu/european-union/about-eu/countries_en#28mem...

Well maybe there’s one way to resolve this dispute?

Did the UK MEPs serve their last day already?