I haven't seen this before, but I just found that if I name a report page "<blank>" (or really anything surrounded by "<>") then it will be... BLANK! Go figure. Guessing this is not a planned feature, but I like it.
Thanks for your sharing.
However, I could not replicate this behavior on my desktop. Which version did you use?
I installed from the store & am a vendor at Microsoft so I have the latest & greatest internal builds that are pushed out. My current build is Version: 2.64.5285.361 64-bit (November 2018). I haven't confirmed that it gets published this way, but Desktop certainly hides the tab name when surrounded by brackets.