Thanks for the info, I tested the code and didn't find a problem, but never now, that's why I'm releasing the code here for everyone to test it themselves or even the developers if they have any thoughts about the time format.

your link doesn't work on follow a 404 page, anyway I have some customer widgets, the only question is the actual content, like RecentPost.php is still overwritten during an update? It is its own PHP file and has nothing to do with the widgets in Wordpress

It's not recommended to use the provided customization as it may lead to conflicts with timezones and show incorrect date and time for users in different timezones. Regarding saving the custom Recent widget and protecting it from wpForo updates, you should consider creating your own custom widget with a different name.

You can refer to detailed documentation on creating a custom WordPress widget here:

This approach will help you achieve the desired functionality without risking conflicts and issues during updates.

	<p class="wpforo-last-post-author">
    <?php wpforo_member_link($member, ''); ?><span class="wpforo-date wpforo-date-ago">, <?php 
    $last_post_date = date("Y-m-d", strtotime($forum . '+1 hour'));
    $current_date = date_i18n('Y-m-d');

    if ($last_post_date === $current_date) {
        echo esc_html__( 'heute um ', 'text-domain' ) . date_i18n('H:i', strtotime($forum . '+1 hour'));
    } elseif ($last_post_date === date_i18n('Y-m-d', strtotime("-1 day"))) {
        echo esc_html__( 'gestern um ', 'text-domain' ) . date_i18n('H:i', strtotime($forum . '+1 hour'));
    } else {
       echo esc_html__( 'am ', 'text-domain' ) . date_i18n('d/m/Y H:i', strtotime($forum . '+1 hour'));
    }
    ?></span>
</p>

and for style 2 topic.php

<div class="wpforo-last-post"><span class="wpforo-last-post-author"><?php wpforo_member_link($last_post_member, ''); ?><span class="wpforo-date wpforo-date-ago">, <?php
        $last_post_date = date("Y-m-d", strtotime($last_post . '+1 hour'));
        $current_date = date_i18n('Y-m-d');

        if ($last_post_date === $current_date) {
            echo esc_html__( 'heute um ', 'text-domain' ) . date_i18n('H:i', strtotime($last_post . '+1 hour'));
        } elseif ($last_post_date === date_i18n('Y-m-d', strtotime("-1 day"))) {
            echo esc_html__( 'gestern um ', 'text-domain' ) . date_i18n('H:i', strtotime($last_post . '+1 hour'));
        } else {
            echo esc_html__( 'am ', 'text-domain' ) . date_i18n('d/m/Y H:i', strtotime($last_post . '+1 hour'));
        }
        ?></span>
    </span>
</div>

by the way, i do not find any way at the moment how i safe the widgtes code outside the plugin that is still work after wpforo plugin have a update, with theme is no problem if you move too wp-theme folder.

Yes, that's how it works, thank you very much 😀 

is fixed with this update: 

<p class="postuser">
    <?php wpforo_phrase( 'by' ) ?> <?php wpforo_member_link( $member ) ?>,
    <span class="uncached" style="white-space: nowrap;">
        <?php
        $last_post_date = date("Y-m-d", strtotime($post . '+1 hour'));
        $current_date = date_i18n('Y-m-d');

        if ($last_post_date === $current_date) {
            echo esc_html__( 'heute um ', 'text-domain' ) . date_i18n('H:i', strtotime($post . '+1 hour'));
        } elseif ($last_post_date === date_i18n('Y-m-d', strtotime("-1 day"))) {
            echo esc_html__( 'gestern um ', 'text-domain' ) . date_i18n('H:i', strtotime($post . '+1 hour'));
        } else {
            echo esc_html__( 'am ', 'text-domain' ) . '<div class="full-date">' . date_i18n('d/m/Y, H:i', strtotime($post . '+1 hour')) . '</div>';
        }
        ?>
    </span>
</p>

I have now tested the code, unfortunately it currently shows the wrong time
e.g. 12:55 instead of 13:55
I am currently looking for the solution how or where to insert the (+1 hour) 😀 

For example, I use

<?php esc_html( wpforo_date( $post, 'd/m/Y g:i a' ) ) ?>

To show the full date and time (without today and yesterday)

But I will test your code, today and yesterday makes the date even clearer 😉 

I know all the settings and have implemented them, but cached content is static and no longer dynamic and with a time format in current minutes and seconds, as in the wpforo standard, this is not particularly advantageous. That's why we made this modification to set it to the time of creation and thought we would share it here or maybe encourage the developers to think about the current system displayed, because the one from an hour ago, a month ago, etc. is pretty flat. This can be useful in forums that may require more precise timing. The whole cacher problem also becomes irrelevant.

yes we use wp-rocket

>>> wpForo and Cache Plugins 😉