Really strongly disagree with those saying recruiting for staff right now is not a red flag. As someone who's worked in a school in a similar situation, recruiting now definitely is.
It is rare for secondary schools to need lots of teachers for an Easter start- most teachers don't like to leave their classes before exams. Yes, I can accept one or two teachers moving on at this time for personal reasons, but it's not a usual break point in secondary. So even if they are recruiting to replace staff planning to leave at Easter, it's a bad sign those staff are choosing not to hang on until the summer holidays.
Because teachers don't like leaving current posts at Easter, it also means that even if they're short staffed now, they will be in the summer term, and that will have a negative impact on the school as a whole.
There are several posters on this thread who are either out of touch with the reality of secondary education in 2022, or just keen to prove how right on they are by pretending they would happily accept this school for their own DC.
The 19% Grade 5s in maths for example is also a problem, because it means they'll maybe have one set sitting the higher paper- covering abilities from a grade 5 to grade 9. This won't be a good experience for those at either extreme of that spectrum. It also means if your child was borderline for getting say a 5/6 I'd be worried about the ability of the school to get them to the higher grade.
If the school is short staffed now/this year, there's every chance things will get worse, rather than get better.
As you have to appeal for a place anyway, it surely makes sense to appeal for a school you're actually happy at.