I loved primary school, didn't really dislike anythibg about it.
Secondary school, agree with PE, ours was always ridiculously under resourced, ie badminton/tennis etc: playing a 10 mins game then sitting around for the other 40 mins as only limited courts. Ditto trampolining, with 20ish kids all taking a turn you basically got 2 mins each. Pointless.
Academically it was the poverty of aspiration I hated in almost every lesson. At least PE was only once a week. In year 7 or 8 my dad said at parents evening that I was bored and not being challenged, could I either have more work or additional work? The response was I was already top of the class and didn't need it.
The same school also didn't set homework for several years in most subjects because the teachers were heavily unionised and 'working to rule'. Thankfully I went to a much more academic 6th form where study and success were actually encouraged.