UMG Background blur does not appear when packaged for android. It will work in PIE at the same preview level but not when packaged for the device.
Found in 4.19 CL# 4033788, 4.20 CL# 4369336, 4.21 CL# 4435744
Background blur from the UMG Widget will appear
The background blur would appear as it did
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-65007 in the post.