I upgraded my MacBook (named macm1) to MacOS Whatever and it seems like the way you input cedilla in the ABC Extended keyboard has changed.
I think that pressing option+c used to output ç but now it’s a dead key for ¸.
A dead key means that the ¸ can be combined with other keys to generate combinations like: ņ, ẹ and of course ç.
You may ask: when would I ever need to type a combination like ¸ or ḩ?
Well, here it is, a blog post that needed it.
Also, my girlfriend is from Galați.