The Gucci caliber GG.V838.MP is an automatic movement with a large moonphase indicator on the dial. This caliber is found in the G-Timeless Moonlight model introduced in March 2022.
The G-Timeless Moonlight’s moonphase display is based on a 29.5 day lunar month. Gucci states that watches with this movement only need adjusting every 360 years. This, of course, is only in theory since you will need to adjust the watch if you stop wearing it and power reserve runs out, or if the watch is in for service.
You may also see this caliber listed as GGV838.MP, but Gucci’s official marketing material writes the number as GG.V838.MP. The MP stands for moonphase. They make some beautiful tourbillon timepieces, but they aren’t great at coming up with caliber numbers… also not great at providing images and detailed specs on their movements.