Going off my previous job as a KS1 teacher, I am not surprised. A vast chunk of my class could not read before coming to school. I had everything from children who couldn't recognise the letters in their own name to ones who found short chapter books too easy! In some cases, I understood, because their parents didn't understand English, or because they (the parents) had learning difficulties. In the latter case, I was touched when the older primary-aged sibling would listen to the one in my class read, and fill in their reading log, as their parents were illiterate. The parent was thrilled that their small child was so good at writing by the age of 5.
In other cases, I was a bit at a loss, e.g. with one parent who thought it more important that her child looked nice than did well academically (the child was pretty, but also very bright), so they didn't get read to/listened to while reading unless they were with their grandparents. Some children seemed to spend most of their time at home looking at screens. Some had parents who rejected any interaction with school, because they didn't see the point in it, and nor did their KS1 children. Others had such difficult lives (think: parents with drug/alcohol/severe mental health issues) that they were trying their best to care for their younger siblings, or were bouncing between foster care and parent(s). At times, it was school that provided stability and a warm meal for them, and anything extra was a bonus, which was heart-breaking at times.
I would listen to all of them read as many times a week as I could, and read a story to them at the end of every day, but there is so little time to do this in the curriculum that it always felt like something had to give way for it.