Yep, Gmail is blocked in Cuba. I was there last year and had the same issue. I used a VPN (NordVPN) and connected to a server in Mexico. It worked after a few tries.
If VPNs are sketchy for you, try accessing your emails through a different device or ask someone back home to forward important stuff to another email provider.
If VPNs are sketchy for you, try accessing your emails through a different device or ask someone back home to forward important stuff to another email provider.