Comment # 8 on bug 1131689 from Marcus R�ckert

so the explanation for the change:

CTRL+V is an established shortcut, also known as paste. using it for activating
autotype was NEVER a good idea. especially since it switches to the last used
window and just starts going without confirmation. adding SHIFT to that adds a
layer of protection.

2nd: I would recommend investigating the official keepassxc browser integration

a) it works really well for me
b) you can configure it to not autofill (the better way), so once you click
into a login field it asks you which credentials to use. and you can decide per
entry if the connected browser should be able to access it.