Page slug of 'testimonials' redirects to homepage

I created a page called ‘Testimonials’ with the page slug of ‘testimonials’, hoping to use the [testimonials] short code to display them all on one page. However, when you go to the url https://www.mywebsite.com/testimonials (for example), it takes you back to the homepage. If I change the page slug to something else it appears to work as intended, but I really want to use the page slug ‘testimonials’.

Is there any reason why this is happening and how I can get it to work as I want?

Many thanks.

https://www.ads-software.com/plugins/clean-testimonials/