Just tested Chrome and Firefox on MacOS Ventura 13.4. The payment links take me to a PayPal website as normal.
I've heard people having problems with the PayPal buttons on mobile. My guess is PayPal is seeing that your device is mobile, and responding with an HTTP redirect to the appropriate app store. I don't have any control over this.
It's possible if you install an extension for your desktop browser that the headers are modified and PayPal gets confused, then chooses the above (mobile) behavior.