Meta Box

Oh, that I did not realized.
So removing these separate plugins:

• MB Blocks
• MB Custom Post Types & Custom Taxonomies
• MB Rank Math
• MB Term Meta
• MB Views
• MB Builder
• MB Conditional Logic

And leaving only Meta Box and Meta Box AIO seem to work just fine.
While keeping active all extensions we need in an Extension tab of the Meta Box plugin itself.
Thank you!

I also know about the rwmb_get_value function, but none of rwmb_* functions returns anything for me.

That works:

{{ my_field }}

That not works: (returns nothing at all)
{{ mb.rwmb_get_value('my_field') }}
{{ mb.rwmb_get_value('my_field', '', post_id) }}

I'm still inside Block Render Settings of Custom Fields, if that means anything.