I written something in a text layer. I increased the size of a specific part of the text with the character panel. I realized that the letterspacing of the words before the selection decreased by nowhere (Big problem when you need to follow specific guidelines for clients 😅). I've recorded an example video with a multiple possibility of selections and the problem only appear when I have 2 lines of text and when I select 2 letters 🤷:male_sign: Same thing for you or it's only me? 😅 (on v22.6.0)
Not sure what you are asking. This is how "real" kerning with paragraph text works, regardless of metric or visual - the text will be fitted into the text block and the engine auto-adjusts the kerning overflow. If you don't want that, use conventional line text or a font with a fixed spacing/ kerning (monospaced).
If you are trying to adjust kerning between two letters, place the cursor between the letters and press Alt/Option and the Left or Right arrow key. If you are trying to adjust the kerning between more than two letters, select all of the layers you want, press Alt/Option and Left or Right arrow to get the kerning setup the way you want it to be.