This issue was fixed in the 1.14.1 Hotfix release. However, it was discovered that the fix caused a different problem (see MCPE-59682), so it was backed out in the 1.14.2 Hotfix release. Mojang is working on a solution that will resolve both issues.
This problem is well understood and its impact (as revealed by the vote count) is fully appreciated, so we don't really need any additional information in the form of additional screen shots and descriptions of it.
It turns out that the fix to
MCPE-59682 did not revert this fix after all. In other words, mobs are not spawning on leaves and glass in 1.14.20. There was some confusion about what it did revert (there have been quite a lot of mob spawning bugs reported in the last few months, and somebody got confused).
I have therefore re-resolved this report as Fixed. If anybody has evidence that it's still occurring, please comment below.