From the article linked by @BidensGranddaughter

The move is largely seen by Maduro’s critics as an attempt to shore up domestic support at home and is also a response to Guyana’s increasingly close military ties with the US . Caracas insists that the referendum is purely consultative and non-binding, and that it has no intention of annexing the territory. But at the same time it is increasing its military activity close to the border with Essequibo, ostensibly to combat illegal mining activities.

and

The government of Guyana is also raising the stakes. Up until last week it had repeatedly denied allegations from Caracas that it was planning to invite US Southern Command to set up a forward operating base in Essequibo. But then last Friday the country’s Vice President Bharrat Jagdeo said in a press conference:

“We have never been interested in military bases, but we have to protect our national interest… We’re going to be working with a number of countries on greater defence cooperation. We will have from the US Department of Defence next week two visits to Guyana, by two teams . And then several other visits in the month of December and then high level representation from the Department of Defence here.”

...That territory is not only rich in oil and gas but also boasts other mineral deposits, including Gold and Bauxite...

The US and Guyana already signed an agreement in 2020 to undertake joint military patrols in the Essequibo region, ostensibly for “drug interdiction” ...