No I’ve noticed that clicking a monzo.me takes you to whichever account you were last on in the app. This issue should go away once the new Labs Feedback: Bill Splitting 📝 feature is released as you send the split request directly to an account and it’s approved in the transaction feed rather than from a link.
Interestingly (if you’re as sad as me) you can’t send a monzo.me link from your personal account, then switch to your joint account and try and pay yourself from your joint account; you get a message stating that you can’t pay yourself.