Which version of Ubuntu you’re installing (including which flavour), Whether you have network connectivity, Hardware stats, including CPU, RAM, GPU, etc, Your device vendor (e.g., Dell, Lenovo, etc), Your country (based on the time zone you pick, not IP), How long your install took to complete, Whether you have auto login enabled, Your disk layout (how many hard drives and partitions you have), Whether you chose to install third party codecs, Whether you chose to download updates during install
(According to OMG!Ubuntu) Most distros offer optional telemetry, but Ubuntu’s is opt out not opt in (for GNOME you have to separately install the telemetry)