I don’t know if this is a bug but while setting up Stripe I turned it on as default and enabled.
It all worked well but while tesing Cash, PayPal Express and Stripe selection I was unable to change from Stripe or to Stripe from one of the other payment options after reloading the page.
Of course, reloading the page is not really likely to be done by the customer but it could happen. Anyway, that’s not my issue. I think that I was unable to change payment types because after reloading, the customer details were removed and these are required for Stripe selection. Also, it seems, for Stripe de-selection because although the customer fields were blank the Stripe was still selected. Before I realised this I opened the Stripe payment config in admin and turned off the default setting. The Stripe payment admin page then became inaccessible with a 500 error and I had to go back in browser history to another page. There was no way back in to that instance of my Stripe setup even after disabling it from the intial list of payment methods (/admin/payments). I had to delete the broken one and create a new one.