Hello there,
Thanks for reaching out! Hmmm... I think you may be referring to having selected a different button action on some of your sites rather than a version issue. There's multiple different WhatsApp button actions that look slightly different, and it looks like you have different actions selected for different sites.
This site for example is using "WhatsApp widget" for the button action, which pulls up a little window on the same page:
Your Sobha-Hartland site meanwhile is using "WhatsApp chat" for the button action, which will pull up a chat through the actual app (so it will be a new tab/leaving the website to open the actual app). I believe that you want all sites to behave like the above screenshot. In that case, you would want to make sure to change the button action to "WhatsApp widget" instead of "WhatsApp chat" on all of your sites.
Let me know if that helps, or please clarify the issue you are having if I was not understanding correctly. Cheers!