Honestly, your theme currently needs quite a bit of attention. At the moment, many elements are not displaying correctly, which makes it difficult to provide a reliable solution in this situation.
I would recommend either maintaining and fixing the current theme or considering installing a new, well-structured theme to ensure everything works smoothly.
You’re applying two classes to your icons, material-icons and material-symbols-outlined, while you must use only the first one for them. Since you’ve applied both, the second one takes over, but does not have required icons.
Looks like you’re using BlockyApp for this, so can be a matter of settings, or a glitch in the app.