The "btn-outline-primary" button has a white background with blue text in a blue border. If "hover", it becomes blue with white text.

But if the button is associated with a link that has already been clicked on, it becomes blue with blue text; thus the text is unreadable.

Where can I change the color?
The screenshots show two buttons; the top one is simple and the bottom one is with a link. Both are in hover mode.