@makaylaglynn Let me preface by saying that I've never had a problem with Revolut, so I'm not one of those anti-Revolut shills. I've been using it for more than 5 years without any issues. I added my paycheck when I first started using it to expand my transfer limits.
However, I've never really put too much money into it. Riskiest thing I've done is transfer 5k from a third person account from outside the EEA and everything was fine.
That said, I have a history with the bank. I have used it for legitimate purposes for a long time so I'm not the kind of account that's usually caught by AML regulations. On the other hand, a brand new account transferring 300k out of nowhere is almost sure to trigger anti money laundering procedures. In this case they will lock your account and make you go through the ringer to prove the funds are yours. At the end, which may take months, they may decide to simply return the money to where it came from.
A brick and mortar bank operates quite differently. They are not so gung-ho on AML because they don't need to be: they won't lose their license any time soon. You can also establish trust much better by coming in a branch and explaining the situation face to face. They at least know you're a real person and not some sock puppet in Russia with cloned documents. Finally, they usually want customers with high savings who they can sell their shitty funds to, so they will at least hear you out.
My advice, walk into a brick and mortar bank, ideally an international bank like HSBC and request speaking to the manager. Then explain that you want to open an account for your 300k on Paypal and would like to consider investing it. You don't have to invest it with them, but this will encourage the manager to help you. Make sure you bring all your invoices and taxes, even if as a show of good faith. Bring your ID (more than one it you have), residence permit, anmeldung if you need it where you live and anything else which you think might be useful. Make sure you check the bank website before on documents. Good luck!