Edit History

J'ai finalement trouvé en quelques minutes.

Si toutefois quelqu'un souhaite désactiver cette fonctionnalité sur cette même série de thème (Posthemes Drama) la solution est:
/themes/(nom_du_theme)/assets/js et le nom du fichier est "custom.js". Recherchez "easyzoom" et supprimez toute cette partie (perso, je l'ai mise en "commentaire").

Le code à supprimer (ou mettre en commentaire) est celui-ci:

/*!
 * @name        easyzoom
 * @author       <>
 * @modified    Thursday, November 22nd, 2018
 * @version     2.5.2
 */
/!*
!function(t,e){"use strict";"function"==typeof define&&define.amd?define(["jquery"],function(t){e(t)}):"object"==typeof module&&module.exports?module.exports=t.EasyZoom=e(require("jquery")):t.EasyZoom=e(t.jQuery)}(this,function(i){"use strict";var c,d,l,p,u,f,o={loadingNotice:"Loading image",errorNotice:"The image could not be loaded",errorDuration:2500,linkAttribute:"href",preventClicks:!0,beforeShow:i.noop,beforeHide:i.noop,onShow:i.noop,onHide:i.noop,onMove:i.noop};function s(t,e){this.$target=i(t),this.opts=i.extend({},o,e,this.$target.data()),void 0===this.isOpen&&this._init()}return s.prototype._init=function(){this.$link=this.$target.find("a"),this.$image=this.$target.find("img"),this.$flyout=i('<div class="easyzoom-flyout" />'),this.$notice=i('<div class="easyzoom-notice" />'),this.$target.on({"mousemove.easyzoom touchmove.easyzoom":i.proxy(this._onMove,this),"mouseleave.easyzoom touchend.easyzoom":i.proxy(this._onLeave,this),"mouseenter.easyzoom touchstart.easyzoom":i.proxy(this._onEnter,this)}),this.opts.preventClicks&&this.$target.on("click.easyzoom",function(t){t.preventDefault()})},s.prototype.show=function(t,e){var o=this;if(!1!==this.opts.beforeShow.call(this)){if(!this.isReady)return this._loadImage(this.$link.attr(this.opts.linkAttribute),function(){!o.isMouseOver&&e||o.show(t)});this.$target.append(this.$flyout);var i=this.$target.outerWidth(),s=this.$target.outerHeight(),h=this.$flyout.width(),n=this.$flyout.height(),a=this.$zoom.width(),r=this.$zoom.height();(c=a-h)<0&&(c=0),(d=r-n)<0&&(d=0),l=c/i,p=d/s,this.isOpen=!0,this.opts.onShow.call(this),t&&this._move(t)}},s.prototype._onEnter=function(t){var e=t.originalEvent.touches;this.isMouseOver=!0,e&&1!=e.length||(t.preventDefault(),this.show(t,!0))},s.prototype._onMove=function(t){this.isOpen&&(t.preventDefault(),this._move(t))},s.prototype._onLeave=function(){this.isMouseOver=!1,this.isOpen&&this.hide()},s.prototype._onLoad=function(t){t.currentTarget.width&&(this.isReady=!0,this.$notice.detach(),this.$flyout.html(this.$zoom),this.$target.removeClass("is-loading").addClass("is-ready"),t.data.call&&t.data())},s.prototype._onError=function(){var t=this;this.$notice.text(this.opts.errorNotice),this.$target.removeClass("is-loading").addClass("is-error"),this.detachNotice=setTimeout(function(){t.$notice.detach(),t.detachNotice=null},this.opts.errorDuration)},s.prototype._loadImage=function(t,e){var o=new Image;this.$target.addClass("is-loading").append(this.$notice.text(this.opts.loadingNotice)),this.$zoom=i(o).on("error",i.proxy(this._onError,this)).on("load",e,i.proxy(this._onLoad,this)),o.style.position="absolute",o.src=t},s.prototype._move=function(t){if(0===t.type.indexOf("touch")){var e=t.touches||t.originalEvent.touches;u=e[0].pageX,f=e[0].pageY}else u=t.pageX||u,f=t.pageY||f;var o=this.$target.offset(),i=f-o.top,s=u-o.left,h=Math.ceil(i*p),n=Math.ceil(s*l);if(n<0||h<0||c<n||d<h)this.hide();else{var a=-1*h,r=-1*n;this.$zoom.css({top:a,left:r}),this.opts.onMove.call(this,a,r)}},s.prototype.hide=function(){this.isOpen&&!1!==this.opts.beforeHide.call(this)&&(this.$flyout.detach(),this.isOpen=!1,this.opts.onHide.call(this))},s.prototype.swap=function(t,e,o){this.hide(),this.isReady=!1,this.detachNotice&&clearTimeout(this.detachNotice),this.$notice.parent().length&&this.$notice.detach(),this.$target.removeClass("is-loading is-ready is-error"),this.$image.attr({src:t,srcset:i.isArray(o)?o.join():o}),this.$link.attr(this.opts.linkAttribute,e)},s.prototype.teardown=function(){this.hide(),this.$target.off(".easyzoom").removeClass("is-loading is-ready is-error"),this.detachNotice&&clearTimeout(this.detachNotice),delete this.$link,delete this.$zoom,delete this.$image,delete this.$notice,delete this.$flyout,delete this.isOpen,delete this.isReady},i.fn.easyZoom=function(e){return this.each(function(){var t=i.data(this,"easyZoom");t?void 0===t.isOpen&&t._init():i.data(this,"easyZoom",new s(this,e))})},s}); 
*/