User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0
Steps to reproduce:
Launch Firefox with MOZ_ENABLE_WAYLAND=1 MOZ_WEBRENDER=1
Firefox loads an empty window
Firefox displays content. This was the case with Firefox about a year ago, this regressed at some point. I did not test it frequently as up until the recent Nvidia 470 series drivers, Xwayland wasn't available so I used X11 as my primary desktop.
This is the furthest mozregression could get, further builds were not available due to the age of the regression:
6:42.71 INFO: Narrowed nightly regression window from [2020-04-20, 2020-04-22] (2 days) to [2020-04-20, 2020-04-21] (1 days) (~0 steps left)
6:42.71 INFO: Got as far as we can go bisecting nightlies...
6:42.71 INFO: Last good revision: 272e82616218411bfb0b89ef7c710cd65830ece1 (2020-04-20)
6:42.71 INFO: First bad revision: 263963426b561b2aa687aeeaeddc4fd93fff9e57 (2020-04-21)
6:42.71 INFO: Pushlog:
6:42.71 INFO: Switching bisection method to taskcluster
6:42.71 INFO: Getting mozilla-central builds between 272e82616218411bfb0b89ef7c710cd65830ece1 and 263963426b561b2aa687aeeaeddc4fd93fff9e57