Downstairs toilet bowl slow drainage

[Brutal biff]

My downstairs toilet bowl is drainage is slow when flushed it will rise to the top then slowly drain.

Ive tried using a plunger and a toilet snake to no avail the drainage is so slow it won' even shift a small piece of toilet paper I've got 2 other toilets that work fine so I don' think it' a soil pipe issue any thing else I can try before calling out a plumber?

 

[Brutal biff]

Gave up called a plumber should be round end of the week as it' not an emergency

 

[Brutal biff]

Would this be an old syphonic toilet by any chance ?? - I cleared one once with drain rod with the rubber disk thing - - slowly pushed it in then pushed hard and it went.

No its a new style toilet with the push button flusher at the top it' about 3 years old the house is a new build about 3 years ago when we moved In

 

[Brutal biff]

Problem seemed to have fixed itself wife used the toilet upstairs and apparently the shower plug hole farted when the toilet was flushed and downstairs toilet now flushing fine

Wierd but least I'm able cancel the plumber