OnePlus has recently updated the 6 and 6T, its second-last generation of flagship phones. The upgrade confers the June 2019 security patch level on the devices. It also adds a native screen-recorder, which is now found in the series' Quick Settings in their UI.
https://www.notebookcheck.net/The-OnePlus-6-and-6T-get-screen-recorders-in-their-latest-software-update.426948.0.html