I've tried it on desktop - Chrome and Firefox and both no longer seem to have this toggle anymore - now it seems that "press enter to send" is the only option.

I've always used carriage returns in messages to separate different thoughts. After "press enter to send" became the only option on desktop, I kept sending half-finished messages while trying to put breaks in them. If you're sending it to someone you haven't matched yet with, you don't get the chance to add to the message and it just looks like another low effort message to the person receiving it. This is super frustrating when you had a lot more to add and had already crafted the message in your head, but then it gets sent as a 3 word message!

Sorry for the rant, but I felt it was really important to get the feedback out there if this was an intentional change, or perhaps get some instruction on how to untoggle the option if I'm just doing something wrong.