UK Visit visa got refused wrongly when should I re-apply? [duplicate]

Let's consider the issues with your application.

1. You are trying to be a tourist in a pandemic. If you were granted the visa you asked for, the reality is that you would spend most, if not all, of your six day visit in quarantine. That would render the visit entirely pointless, and makes them think you have some other reason for wanting to visit - specifically that you would "go underground" when you arrived and attempt to live and work in the UK illegally.
2. You failed to do even minimal research into the costs and opening of the tourist sites you said you wanted to visit. This again leads them to think you are really intending to live and work illegally in the UK.
3. The job you have is temporary and could be done from anywhere in the world. This means you have no reason to return to Pakistan after your visit, and puts you at high risk of failing to leave the UK.
4. I can't comment on whether your freelancing income is really taxable. If you are right it is probably a simple mistake by the processing office. It is unlikely that this would have made a difference to your application.
5. Your finances are such that it would be hard for the officer to believe you were genuinely spending six months of your income on something that is simply a tourist trip. This again leads them to believe that you have a different reason for your trip.

There is no simple fix that would get you a visa next time. Not only are there fundamental issues with finances and ties to your home, but you also have made an application that looks like it was not in good faith. (It doesn't matter whether it was really genuine, it only matters what it looks like to the officer.) This is likely to affect future applications, meaning you will need even better evidence of your intention to return to Pakistan. You would probably be better off looking to travel to somewhere else for your tourism.

As @DJClayworth already said: Your income is absolutely not the problem. Even if you "fix" or explain the numbers stuff, it doesn't matter.

The real reason is that they do not believe you will go back home again. And honestly: It's a very justified call. ALL the signs point towards you staying longer in the UK, very cliche even so. Your travel calculations are off, you're trying to tourist-travel during a pandemic, spending a significant amount of your income for mostly chilling in quarantine, it just does not add up. Remember that your true intentions don't matter, only how certain THEY (immigration agents) are that your intentions are purely tourist. And for that certainty (on THEIR part), all the signs are bad.

What do you need to fix? You need to show that you have definitive, impactful reasons to go back. You need to convince them that you are the tourist that you are planning to be.

That could be a good job in your home country.

"Your employment therefore does not demonstrate a tie to your home country". You have a good job, that is true, but it needs to be a good job that is keeping you in your home country, which is absolutely not the case with yours.

That could be a family or significant assets in your home country like a family and/or a house. Though I'm not certain how much that would count since leaving despite a family and visiting them frequently is not too uncommon.

And on top of that, your story of what you plan in the UK needs to be very plausible. As a Pakistani citizen, and especially as one with your background, you are on maximum suspicion level, a half-assed travel plan is the last thing you want. You need EVERYTHING to be 100% ´good, correct and meaningful. And that likely includes not traveling during a pandemic.

It might be as well that they're just denying all tourist visas at the moment anyway, and they just gave your application to a trainee to find good reasons, so he went overboard.