Really helpful chart to consider guidance for font size depending on viewing mode i.e. f2f vs online display of slide decks. I’m now off to try out 5pt font to view online!
Consistency of font size between slides feels important to reduce eye strain of refocusing.
This might help: a chart I found and used when explaining text size for displays. So, no, you aren't over thinking. The nearer, the smaller font can be and vice versa. As you would expect.