The triple brace syntax for filtered transclusion works differently according to whether it is invoked in “block mode” or “inline mode”.
Block mode is triggered if the transclusion appears at the start of a block and is immediately followed by a line break. Otherwise the transclusion will be rendered in inline mode.
In block mode, the output is displayed as one link per line. In inline mode, the output is squooshed together into a single line. Inline mode is more useful when using a template.
Thank you Jeremy!
Then one can expect an output in inline or block mode! but why above example returns an empty triple braces when inline mode is triggered by adding a space to first line? E.g
{{{ [all[current]get[created]format:date[0hh:0mm 0DD-0MM-YYYY]] }}} space
{{{ [all[current]get[created]format:date[0hh:0mm 0DD-0MM-YYYY]] }}}
The problem here is that there is a space character immediately after {{{ [[20220101]format:date[]] }}}; remove it and the result is as expected. I agree that it’s confusing behaviour; see my explanation above for why it occurs.