Prestashop 1.7.6/ PHP 5.6

[gtul]

Hello,

I have a new Prestashop 1.7.6 site and I just changed the hosting server.

My site was not displayed correctly so I contacted technical support and I was told this:

Issue is that you are using PHP 7.4 in your hosting while this site requires an old PHP 5.6
I just put PHP 5.6 instead of 7.4 in your hosting and the site is now working
on the other hand it is not very good to run old sites not compatible with php7.x

Can someone explain to me why a new Prestashop 1.7.6 requires the use of a PHP 5.6 instead of a PHP 7.4?