This region has always been disputed, but Guyana recently discovered a bunch of oil, a portion of which is off the coast of the disputed area. The issue has basically been dormant for decades, because the region in question despite being 90% of the land area of Guyana has only 10-15% of the population, mostly Indigenous villages. However, it was never formally resolved, which means the countries' coastal economic zone was never resolved either. This would also be fine, except Guyana has already got involved with Exxon to start exploring oil reserves in the contested offshore area, so Venezuela has to do something now or else the precedent will be set that it belongs to Guyana, which will be almost impossible to undo.

Frankly I don't think either side here is prepared for a full-scale military conflict, I think Venezuela will annex the territory by just starting to provide administration to the region, build roads etc. and claim that as it was essentially not being administered to before (and it really wasn't), Guyana has lost claim to it. Nor does Guyana have the resources to start administering it properly, because as a US/Western puppet they've been thoroughly drained the same way every latin american puppet has. So what I'm really hoping is Venezuela can just peacefully push them out through simple economic, administrative means.