". This includes numbers, "true/false", etc. If you wrap characters in quotation marks, you'll create a string.
!=operators and related functions.
\in order to represented property in a Notion formula.
"will become un-escaped whenever you re-open and edit your formula. You'll need to re-escape them every time you make an edit.
'do not need to be escaped. If you wrap a string in single quotes, they'll be converted to double quotes the next time you open the formula for editing.