Default lazy loading cannot display placeholder images, which feels strange. Some people in the community say to delete

&&!e.attr("src")

but after testing, it reported a large number of errors.

After repeated testing, changing

&&!e.attr("src")

to

&& e.attr("lay-src")

can solve the problem.
Demo address: https://www.7ca.com.cn
Complete code (file path: /lay/modules/flow.js)

/** layui-v2.2.6 MIT License By https://www.layui.com */
;
layui.define("jquery",
    function(e) {
        "use strict";
        var l = layui.$,
            o = function(e) {},
            t = '<i class="layui-anim layui-anim-rotate layui-anim-loop layui-icon "></i>';
        o.prototype.load = function(e) {
            var o, i, n, r, a = this,
                c = 0;
            e = e || {};
            var f = l(e.elem);
            if (f[0]) {
                var m = l(e.scrollElem || document),
                    u = e.mb || 50,
                    s = !("isAuto" in e) || e.isAuto,
                    v = e.end || "No more",
                    y = e.scrollElem && e.scrollElem !== document,
                    d = '<cite>Load more</cite>';
                    h = l('<div class="layui-flow-more"><a href="javascript:;">' + d + '</a></div>');
                f.find(".layui-flow-more")[0] || f.append(h);
                var p = function(e, t) {
                        e = l(e),
                            h.before(e),
                            t = 0 == t || null,
                            t ? h.html(v) : h.find("a").html(d),
                            i = t,
                            o = null,
                        n && n()
                    },
                    g = function() {
                        o = !0,
                            h.find("a").html(t),
                        "function" == typeof e.done && e.done(++c, p)
                    };
                if (g(), h.find("a").on("click",
                    function() {
                        l(this);
                        i || o || g()
                    }), e.isLazyimg) var n = a.lazyimg({
                    elem: e.elem + " img",
                    scrollElem: e.scrollElem
                });
                return s ? (m.on("scroll",
                    function() {
                        var e = l(this),
                            t = e.scrollTop();
                        r && clearTimeout(r),
                        i || (r = setTimeout(function() {
                                var i = y ? e.height() : l(window).height(),
                                    n = y ? e.prop("scrollHeight") : document.documentElement.scrollHeight;
                                n - t - i <= u && (o || g())
                            },
                            100))
                    }), a) : a
            }
        },
            o.prototype.lazyimg = function(e) {
                var o, t = this,
                    i = 0;
                e = e || {};
                var n = l(e.scrollElem || document),
                    r = e.elem || "img",
                    a = e.scrollElem && e.scrollElem !== document,
                    c = function(e, l) {
                        var o = n.scrollTop(),
                            r = o + l,
                            c = a ?
                                function() {
                                    return e.offset().top - n.offset().top + o
                                } () : e.offset().top;
                        if (c >= o && c <= r && e.attr("lay-src")) {
                            var m = e.attr("lay-src");
                            layui.img(m,
                                function() {
                                    var l = t.lazyimg.elem.eq(i);
                                    e.attr("src", m).removeAttr("lay-src")
                                        , l[0] && f(l)
                                        ,i++
                                })
                        }
                    },
                    f = function(e, o) {
                        var f = a ? (o || n).height() : l(window).height(),
                            m = n.scrollTop(),
                            u = m + f;
                        if (t.lazyimg.elem = l(r), e) c(e, f);
                        else for (var s = 0; s < t.lazyimg.elem.length; s++) {
                            var v = t.lazyimg.elem.eq(s),
                                y = a ?
                                    function() {
                                        return v.offset().top - n.offset().top + m
                                    } () : v.offset().top;
                            if (c(v, f), i = s, y > u) break
                        }
                    };
                if (f(), !o) {
                    var m;
                    n.on("scroll",
                        function() {
                            var e = l(this);
                            m && clearTimeout(m),
                                m = setTimeout(function() {
                                        f(null, e)
                                    },
                                    50)
                        }),
                        o = !0
                }
                return f
            },
            e("flow", new o)
    });