Want the Approve/Deny buttons to disappear once ticket is approved.

Ah, yes.  You need to get your mind right as described in the link here.

dynamic form rules and or | Qrew Discussions

Instead of writing a rule per situation, you need to make a form rule per field.  That way you will not have multiple rules competing to try to show/hide on the same field.

Now that I solved the issue of the help text, I'm trying to address the issue of showing/hiding the approval/denial buttons.

I have a form rule already for the Approve button to only show when a projected completion date is entered (see attached Screenshot 1). Once the ticket has been approved by our manager, and assigned to a team member to work on it, once the team member opens the ticket to view it, and clicks the Edit icon to enter their notes or anything else they may need to do, those four buttons are still showing. I want to make it so that those four buttons do not show once the ticket has been approved. I tried writing another form rule to do this (see attached Screenshot 2), but it seems there may be a conflict with the form rule I already created in Screenshot 1, because it's not working properly; all of the other buttons except for the "Approve" buttons disappear (see attached Screenshot 3). It seems there is some conflict with two form rules for the same field. How can I resolve this?

You can use a Form Rule to control the Show / Hide on fields.  As for hiding the instructional text, you cannot use a form rule to show/ hide on a Rich Text element on a form.  So you would either need to put that message in a section, and then control the section by a form rule, or else make a Rich Text formula field to make a similar message, and then use that on the form instead of the Rich Text Element.