I expect that processing delays depend on several factors among which is difficulty verifying the information you presented in your application due to delays
in answers from the sources (government, bank, etc..).
My application was initially set for Fall 2020, but the semester had already started in August 31 so I had to defer until January and I was losing my mind because the procession was taking too long. I updated the IRCC with my new LOA.. not sure if that's going to put more delays on the visa decision.