Can you get shiny blocked?

I feel like I've been blocked for getting shiny mons.

My shiny luck has never been stellar but I can usually say least get them here and there and on community days but

Over the last 150 raids on legendaries since the beginning of August I've encountered 0 shiny, also the last 3 community days I've encountered 0 shiny mons despite having caught 200+ mons each on those days ( of the community day mon).

Is that a thing? Or am I just having extra bad luck?

I'm not usually a shiny hunter but I did want a shiny unicorn so kinda bummed there.