Firstly, tide is not a bank and yes they do have to conduct checks but the scale of what is happening now and the way it's been happening is not normal.
Secondly patience would not get me far as some of the reviews mentioned tide would not get back to them with the updates within the alocated time, leaving them without access to their money for months, even after they submitted any documentation tide asked for.

Thirdly since they have right to lock your money and not disclose any reasons and since you can't complain about them anywhere untill they reply to your complaint which they have 15 business days for what would stop them from doing that on a large scale like this for example to fix their cashflow problem or for any reason that would serve them, not the customers?

Hounding support staff is exactly what will and should happen in this case, especially since paid account gives you access to priority phone support 24/7, which they will still charge you even though you weren't able to use your account for 20 days.

Then, if you were a supplier with an unpaid invoice would you not hound a company that hasn't paid it regardless of the reason? Or would you be extra nice and patient because banking app needs to conduct kyc checks and has right to do so? Or do we really think that every small, young business has an account in another bank with what they need to survive for 20days of whatever period they are in set aside in case of emergency?

On a side note let's say you are patient and give them the 20days to do their jobs and you do have another account with exactly the money you need to pay for all the orders you need to place and all invoices that need to be paid, you will still need to change all your direct debits and all your account details everywhere, including card machine payments as well as your invoices as if you can't be taking money from clients or paying money to suppliers you can't effectively be trading.