Firstly, teaching some online and some in class is really tough. I've done it in the last 2 terms - I've been teaching almost 30 years and I work in a lovely school. It was really hard work. Having 32 in the class is a breeze in comparison.
Not all state schools are terrible. Mine is lovely. Some private schools are appalling. I know, I have taught in both. I detest the sense of entitlement in some private schools here; the "you can't tell us what to do, our parents pay" mentality sucks.
Some of the issues in the OP are possibly down to poor teaching/classroom management and a lack of SLT support. But teachers now have to deal with kids who a generation ago would not have been in mainstream education. Special schools are full, local authorities cannot afford to send kids to private alternative provision so often these poor kids are floundering along in mainstream, often in the bottom sets, because there is nowhere else for them.
The curriculum since it was "Gove-d" has become ridiculous in terms of the content that has to be covered. Lots of kids (and teachers) don't see the point and kids who are already struggling with motivation, behaviour, different learning needs etc just cannot cope.
What education needs is to be funded properly, the curriculum designed by people who actually know the job rather than some politician trying to make a point, ready access to services which help and support learning needs (more funding there too) and people to step up and actually parent their kids. Until we get that, I can't see things improving.