Is this common in contracts??
[0] And often, I'm told, companies have the upper hand here, because they can often show that almost anything is related to their particular activities.
I also have something like "should not work in similar area within The UK". Again, how would they know? This conflicts with data protection act, therefore invalid.
They could guess that I didn't create it in the last two weeks, but then good luck proving it in court.
I have much better relationship with my employer now, If I hadn't I would quit tomorrow.
They could get expert testimony about the amount of time it took to create, find old stack exchange questions let alone get court ordered access to git etc. They may not end up winning, but you could settle just to avoid the cost.
On the other hand, this definitely counts as "nice problem to have" and probably isn't worth actually worrying about.
For other social media then just keep your nose clean and stick to posting content and discussing stuff that doesn't mention work.
But that said unless you stole your previous employer's crown jewels (customer lists, source code, IP etc) then these clauses would get thrown out if you were taken to court. Imagine a Volkswagen car dealership trying to limit, contractually, the employment opportunities of their mechanics or sales people from moving down the road to the Ford dealership for better hours/pay/commission. They'd be laughed out of the court room I think.
One company bought the other.