With everyone moving to Chromium for browser development, Firefox stands alone. And, in standing alone, the company needs to continue to deliver quality builds with fewer bugs.
Recently, the distribution of build 65 had to be halted due to an issue with Avast and https sites. Now, the company has had to halt distribution of build 66 until a bug in PowerPoint online can be resolved.
Steps to reproduce:
Update Firefox to latest (66)
Open Microsoft 365 online.
Try to type anything anywhere.
Text vanishes forever
Text appears in box like normal
According to the original the bug submission (Bug 1536453) thread, a fix is available and distribution should resume soon. If you or your users experience the PowerPoint bug, just wait for the update.