"typo3fluid/fluid": "^3.0"
Feature Request
TYPO3 10.4 supports fluid 3. The blog extension restricts to fluid 2.x.
Is the blog extension specifically incompatible with fluid 3.0?
@LeoniePhiline we have not testet compat support yet, will have a look today
After some tests, i would consider fluid 3.0 breaking and not finished. That means we can not provide support for Fluid 3.0 until it´s fixed in fluid.
Example 1: Not able to pass/save dynamic array key.
<f:variable name="publishDateFormat" value="{settings.meta.{metatype}.elements.published.format}" />
<f:debug>{settings.meta.{metatype}.elements.published.format}</f:debug>
<f:debug>{publishDateFormat}</f:debug>

Example 2: Unable to find sections within the same templates.
<f:variable name="name">authors</f:variable>
<f:variable name="icon"><f:render partial="General/BlogIcons" section="Author" optional="true" /></f:variable>
<f:variable name="prefix"><f:translate key="meta.authors.author"/></f:variable>
<f:if condition="{post.authors}">
<f:if condition="{post.authors} > 1">
<f:variable name="prefix"><f:translate key="meta.author.authors"/></f:variable>
</f:if>
<f:render partial="Meta/Rendering/Item" arguments="{name: name, icon: icon, prefix: prefix}" contentAs="content">
<ul class="postmetagroup__list">
<f:for each="{post.authors}" as="author">
<li>
<f:render section="ProfileLink" arguments="{author: authors}" contentAs="content">{author.name}</f:render>
</li>
</f:for>
</ul>
</f:render>
</f:if>
<f:section name="ProfileLink">
<f:if condition="{author.profile}">
<f:then><a rel="author" href="{author.profile}"><span itemprop="name">{content}</span></a></f:then>
<f:else><span itemprop="name">{content}</span></f:else>
</f:if>
</f:section>

At this point i consider fluid 3.0 as unusable.
As soon as Fluid 3.0 is released and working we will add support, marked this issue as blocked for now.
@NamelessCoder can you have a look at this?
A fix is pending for (1) - https://github.com/TYPO3/Fluid/pull/524.
(2) has to be investigated but sounds like an issue with the rendering stack not containing the current template as topmost item when the f:render is evaluated, which I suspect is because the statement is contained within another f:render.
Fluid v3 is history. You may close this one.