Item size under 1× do not work ( disappear. )
Here ↓ but same size ( less large expected )
Gone ↓ away ?
I can’t see difference between 1.0 and 1.5×
It’s only bigger than before in 20.04 - so seems like 1.5× is always applied.
System localized in French here where decimal separator is [ , ] and not [ . ] maybe it has some importance.
And those pictures may also serve as illustration for
( look at top left. )