This has been the case of years. My first FOSDEM was about a decade ago and it felt like that then. You go to a room a talk or two before the talk you actually want to see because of the queues, which means you’re in a talk you didn’t necessarily want to go to, at the expense of someone who might have wanted to. So they’ll queue a talk or two ahead next time, ad infinitum
If you are going to specific devrooms instead of specific talks, you usually don't need to wait in line before getting in. At least that was my experience last year: I got there early in the morning and the rooms were not very full.
Last time I went was 2018, I don't really remember any queues back then. I might be misremembering, but I do remember attending a lot of the talks I wanted to.
