Just ran into a strange issue where merging makes some mistakes on {} brackets.
Using your demo1, tested the following:

Left editor:

let flipSpeed = 55

function setup() {
	createCanvas(windowWidth, windowHeight)
	background(255)
}

function draw() {
	background(0)
}

Right editor:

function setup() {
	createCanvas(windowWidth, windowHeight)

}

function draw() {

}

What it looks like initially:

After the first two merges (shows mistake):

Then corrects itself if I add an extra line (only if removing the indented tab):